Asymptomatic and Sub-microscopic Plasmodium Falciparum Infection in Children in the Mount Cameroon Area: a Cross-sectional Study on Altitudinal Influence, Haematological Parameters and Risk Factors

Asymptomatic and Sub-microscopic Plasmodium Falciparum Infection in Children in the Mount Cameroon Area: a Cross-sectional Study on Altitudinal Influence, Haematological Parameters and Risk Factors | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Asymptomatic and Sub-microscopic Plasmodium Falciparum Infection in Children in the Mount Cameroon Area: a Cross-sectional Study on Altitudinal Influence, Haematological Parameters and Risk Factors Irene Ule Ngole sumbele, Rene Ning Teh, Gillian Asoba Nkeudem, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-310174/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Background: The Mount Cameroon area has experienced a 57.2% decline in confirmed malaria cases between 2006 and 2013 with the implementation of different control measures but, the disease is still of public health concern. The objective of the study was to assess the burden of asymptomatic and sub-microscopic Plasmodium infection, altitudinal influence on it, their effect on haematological parameters as well as identify the risk factors of infection. Methodology: A cross-sectional community-based survey involving 1319 children of both sexes aged 6 months to 14 years was conducted between July 2017 and May 2018. Asymptomatic malaria parasitaemia was confirmed by Giemsa-stained microscopy, sub-microscopic Plasmodium infection by 18S mRNA using nested PCR and full blood count analysis was done using an auto haematology analyser. Results: Malaria parasite, asymptomatic and sub-microscopic Plasmodium infection and anaemia were prevalent in 36.4%, 34.0%, 43.8% and 62.3% of the children, respectively. The risk of having sub-microscopic Plasmodium infection was highest in children 5‒9 (OR = 3.13, P < 0.001) and 10‒14 years of age (OR = 8.18, P < 0.001), non-insecticide treated net users (OR = 1.69, P < 0.04) and those anaemic (OR = 9.01, P < 0.001). Children with sub-microscopic infection had a significantly lower mean haemoglobin (9.86 ± 1.7 g/dL, P < 0.001), red blood cell counts (4.48 ± 1.1 x 1012/L, P < 0.001), haematocrit (31.92%, P < 0.001), mean corpuscular haemoglobin concentration (313.25 ± 47.36, P = 0.035) and platelet counts (280.83 ± 112.62, P < 0.001) than their negative counterparts. Children <5 years old (73.8%), having asymptomatic (69.8%) and sub-microscopic Plasmodium infection (78.3%) as well as resident in the middle belt (72.7%) had a higher prevalence of anaemia than their peers. Conclusion: The significant heterogeneity in the burden of asymptomatic and sub-microscopic Plasmodium infection in addition to its corollary on haematological variables among children in the different attitudinal sites of the Mount Cameroon Region accentuate the need for strategic context specific planning of malaria control and preventative measures. Infectious Diseases Anaemia asymptomatic malaria children haematological parameters sub-microscopic infection Plasmodium falciparum risk factors Cameroon Figures Figure 1 Figure 2 Figure 3 Background Globally, malaria is still a public health concern, although the death cases have steadily reduced from 736000 in 2000 to 409000 deaths in 2019. Cameroon accounts for 3% of this number [ 1 ], even with the recommended world health organization (WHO) control measures put in place [ 2 ]. In some malaria endemic areas, particularly Cameroon, where the disease burden is diverse, variations between altitudes and geographical areas [ 3 , 4 ] may necessitate a strategic control measure. Falciparum malaria continues to negatively impact human life and in malaria-endemic countries, many Plasmodium falciparum infections manifest through various outcomes ranging from asymptomatic infection to the complicated disease, depending on the parasite density [ 5 , 6 ]. Asymptomatic malaria is defined by the WHO as the presence of asexual parasites in blood, without symptoms of illness [ 7 ]. Other studies defined asymptomatic malaria as the existence of malarial parasitaemia of any density in blood without any symptoms in individuals who have not received recent antimalarial treatment in a given population [ 8 ]. This definition includes early detection of rising parasitaemia or any density of parasitised red blood cell (RBC) that is not enough to trigger a fever response [ 5 ]. Several studies in the central and East part of Africa have reported great numbers of asymptomatic malaria in endemic communities [ 9 , 10 ]. In some of these communities, asymptomatic malaria parasite carriers represent a persistent pool for maintaining the life cycle and transmission of the Plasmodium species by the anopheline vector [ 11 ]. Also, Gouagna et al . [ 12 ] reported a higher susceptibility of the malaria parasite among asymptomatic carriers when compared to the symptomatic one’s. Sub-microscopic infections are present across different settings and populations [ 13 , 14 ]. Okell et al . [ 15 ] reported that the prevalence of sub-microscopic infections is inversely correlated with slide prevalence and parasite density on the global level. Several reports in low transmission settings have also suggested higher proportions of sub-microscopic infections when compared to microscopically detectable infections particularly in settings where recent malaria control efforts have been successful [ 5 , 16 ]. This may not only be true in low transmission settings but may also be true in highly endemic communities, where a large proportion of sub patent infections may cause a partial non-sterilizing malaria immunity. Thus, it is necessary to uncover the extent of sub-microscopic infection in a high malaria transmission setting such as the Mount Cameroon area. The existence of a significant sub-microscopic infection prevalence in an otherwise asymptomatic, microscopically negative population in Ethiopia [ 14 ] highlights that malaria infections can continue in a community even in the absence of illness. Nevertheless, although rarely causative agent of severe, acute symptoms, sub-microscopic malaria has been associated with several adverse outcomes during pregnancy [ 17 ], as well as mild anaemia [ 18 ] and various other symptoms (coughing, vomiting, jaundice etc.) in children under 10 years [ 19 ] in low endemic areas. However, little is known on its association with altitude and haematological indices especially in areas with moderate to high endemicities. The Mount Cameroon Region represents a meso-hyperendemic setting and malaria epidemiology is highly heterogeneous as seen in many other parts of the country [ 4 , 20 ]. This region has experienced a 57.2% malaria parasitaemia decline in confirmed malaria cases between 2006 and 2013 [ 21 ] mainly attributed to implementation of artemisinin-based combination therapy (ACT) and the wide scale distribution of long-lasting insecticide-treated nets [ 21 ]. In 2011, Cameroon distributed over eight million long-lasting insecticidal nets (LLINs) throughout the country (22). The second nationwide distribution was carried out in 2016 and distributed about 12 million LLINs were distributed. Yet, the disease prevalence is still a public health concern and it remains unclear if this stability in endemicity over the years is associated with asymptomatic or sub-microscopic infections. However, there is no documented study relating the epidemiological characteristics of asymptomatic and sub-microscopic Plasmodium infection and their effects on haematological variables among children living in the different altitudinal sites along the Mount Cameroon area. Hence, determining the prevalence and association with haematological variables in this malaria endemic setting will be fundamental for a strategic control planning and subsequently elimination. Methods Study area and participants The study was carried out in Batoke (Limbe), Dibanda (Buea) and Tole (Buea), which are three semi-rural communities along different altitudinal ranges in the Mount Cameroon area, as shown in Fig. 1. The sites were classified as lowlands ( 600 m asl). The coordinates of Batoke range from altitude 8m asl, latitude 04°01.364′ N, longitude 009°05.971′ E to 47m, 04°02.039′ N and 009°05.808′ E; Dibanda from altitude 358m asl, latitude 04°06.447′ N, longitude 009°18.725′ E to 400m asl, 04°07.179′ N and 009°18.464′ E and Tole is located between 627m asl, latitude 04°07.057′N, longitude 009°15.178′E and 630m asl, latitude 04°6.906′N, longitude 09°14.434′E. These three study sites have been described in detail by Teh et al . [ 3 , 23 ]. The work was conducted among pre- and school aged children of both sexes between 6 months and 14 years old, who granted assent and whose parents/caregivers consented to participate in the study. The inclusion and exclusion criteria of this study were revised according to Teh et al. [ 3 ]. Study design This cross-sectional community-based study was conducted between the months of July 2017 and May 2018. Participants were invited for data collection in each community by their local chiefs and coordination was organised by the head/leader of a block within a neighbourhood (“quarter head”) of the various communities. Potential participants were reminded of the collection dates per block by the head/leader of the block. At the start of the study in each site, the parents, guardians and children were educated on the study protocol and the benefits of participation highlighted at their various neighbourhoods using an information sheet. Upon obtaining informed consent/assent from the parents/care givers, the study team proceeded with the collection of samples at specific identified collect sites. Sample size and sampling techniques The sample size for each study altitude was calculated using the 66.2 % prevalence of malaria in children in the study area [ 24 ]. Sample size was determined using the formula n = Z 2 pq/d 2 [ 25 ] where n = the sample size required, z = 1.96: which is the standard normal deviate (for a 95% confidence interval, CI), p = 66.2%: proportion of malaria prevalence, q = 1 - p: proportion of malaria negative children and d = acceptable error willing to be committed. The minimum sample size was estimated as n = 344 for each site. Considering a possible participation of more than one child per family, loss of samples due to blood clotting and incomplete data entry, the sample size was adjusted by 10% to a minimum of 379. A multistage cluster sampling method was used to obtain the required sample. In the first stage, all the communities in the Mount Cameroon area were stratified into 3 zones namely lowland, Middlebelt and highland. One community was randomly selected from each zone namely, Tole (highland), Dibanda (middle belt) and Batoke (lowland). In the second stage, 21 clusters (quarters) were randomly selected from 31clusters within the three communities. Within the clusters, all the households with children ≤ 14 years of age were selected. In a household where only one child within that age was present, the child was selected automatically. In a case where more than one child was present in a household, only one was randomly selected. A probability proportionate to size sampling method was used to select 400 random malaria negative samples from all the negative samples in the study population for the sub-microscopic studies. Collection of data Sociodemographic data which included information on sex, age, literacy level of parents/caregivers and malaria preventive methods, as well as fever history of participants were collected using a structured questionnaire. Axillary temperature was measured using an electronic thermometer with a febrile condition considered as temperature ≥ 37.5ºC [ 26 ]. Laboratory methods Three to four (3–4) millilitres (mL) of venous blood sample was collected from each child using sterile disposable syringes. Part of the blood sample was used to prepare thick and thin films on the same slide for the determination of the presence of malaria parasite by Giemsa-stain microscopy using standard methods [ 27 ]. Parasite densities were expressed as asexual parasites per µL with reference to the participant’s white blood cell count (WBC) and categorised as low, moderate, high and hyper parasitaemia [ 28 ]. Also, 50 µL of the EDTA blood sample was aliquoted onto a Whatman 3mm filter paper and dried overnight at room temperature. The dried blood spots (DBS) were used to determine sub-microscopic Plasmodium infection. Genomic deoxyribonucleic acid (DNA) was isolated from the DBS using chelex [ 29 ]. Primary and nested polymerase chain reaction (PCR) assays were carried out for all genes. The primary PCR was carried out with a pair of Plasmodium genus-specific primers (rPLU5- 5’CCTGTTGTTGCCTTAAACTTC3’ and rPLUS6- 5’TTAAAATTGTTGCAGTTAAAACG3’) which amplified a 1100-base pair (bp) PCR product from the rRNA small subunit gene (18S rRNA) while the nested primers specific for P. falciparum (rFAL1–5’TTAAACTGGTTTGGGAAAACCAAATATATT3’) and rFal2–5’ACACAATGAACTCAATCATGACTACCCGTC3’) were used, which amplified a 205-bp indicating a P. falciparum infection [ 30 ]. Furthermore, an auto-haematology analyser (Urit-3300® analyser, Guangxi, China) was used to assess haematological parameters following the manufacturer’s instructions and the condition of anaemia was defined as haemoglobin level (Hb) < 11g/dL of whole blood [ 27 ]. Definitions and end points Sub-microscopic infection was defined as low-density blood-stage malaria parasite infection that was not detected by conventional microscopy but positive using PCR. Asymptomatic malaria parasitaemia was defined as the presence of Plasmodium by microscopy and with an axillary temperature of < 37.5°C and no record of fever within the past 2 weeks. Parasitaemia was categorised as low (< 1,000 parasites/µL blood), moderate (1,000‒4,999 parasites/ µL blood), high (5,000‒99,999 parasites/ µL blood), and hyper parasitaemia (≥ 100,000 µL) [ 28 ]. Anaemia was defined as Hb < 11.0 g/dL and further categorized as severe (Hb < 7.0 g/dL), moderate (Hb between 7.0 and 10.0 g/dL), and mild (Hb between 10.1 and < 11 g/dL) [ 26 ] Malarial anaemia (MA) was defined as children with a malaria-positive smear for P. falciparum parasitaemia (of any density) and Hb < 11 g/dL. Statistical analysis Continuous variables were summarized into means and standard deviations (SD) and categorical variables reported as frequencies and percentages, were used to evaluate the descriptive statistics. The differences in proportions were evaluated using Pearson’s Chi-Square (χ 2 ). Group means were compared using Kruskal Wallis and Mann-Whitney U Test. Parasite densities were log transformed before analysis. Associations between predictor variables and primary outcomes were assessed using both bivariate and multivariate logistic regression analysis. Odd ratios (ORs) and 95 % confidence intervals (CIs) were computed. Any covariate with a P value < 0.2 in the bivariate analysis was subsequently included in the final multivariable logistic model. Significant levels were measured at 95% CI with the level of significance set at P < 0.05. Post entry and clean-up of data in Microsoft Excel 2016, analysis was performed using the IBM-Statistical Package for Social Sciences (IBM-SPSS) version 20 and Epi-info version 7. Results Socio–Demographic and Clinical Characteristics of the Study Population A total of 1319 children with a mean (SD) age of 6.0 (3.5) years, residing at lowland (30.7%, 405), middle belt (37.2%, 491) and highland (32.1%, 423) in the Mount Cameroon area were evaluated. As shown in Table 1 , most of the parents/caregiver of the children had a primary (47.9%) and secondary (31.6%) level of education. The proportion of febrile children in the study population was 8.5% (112), with no significant differences in age and sex. The prevalence of malaria and malaria anaemia in the study population was 36.4% and 25.4%% respectively. Children between 5‒9 years had the highest occurrence of malaria (39.4%) at P = 0.021 while those under 5 years had the highest occurrence malaria anaemia (29.4%) when compared with their contemporaries at P < 0.001, respectively. A complete clinical and laboratory data for a total of 1271 and 400 children were used to determine the prevalence of asymptomatic and sub-microscopic malaria infection, respectively. The prevalence of asymptomatic and sub-microscopic malaria infection in the study population was 34.0% and 48.3%, respectively. The prevalence of asymptomatic malaria was significantly highest (P = 0.047) among the 5‒9 years age group (36.9%), while the 10–14 years age group (60.5%) had the highest level of sub microscopic infection (P < 0.001) when compared with the other age groups (Table 1 ). Table 1 Demographic, altitude and clinical characteristics of the participants by age and sex Parameter Age groups in years Sex Total < 5 5–9 10–14 Male Female % (N) 38.1 (503) 42.2 (557) 19.6 (259) 49.4 (652) 50.6 (667) 100 (1319) Mean age (SD) in years 2.5 (1.2) 6.7 (1.4) 11.5 (1.2) 6.3 (3.5) 5.9 (3.5) 6.0 (3.5) Mean haemoglobin (SD) level in g/dL 9.9 (2.0) 10.6 (1.7) 11.2 (1.7) 10.4 (1.8) 10.5 (1.9) 10.5 (1.8) Educational level of parent/caregiver No formal (n) 8.9 (42) 11.9 (57) 7.2 (16) 10.5 (61) 9.2 (54) 9.8 (115) Primary (n) 42.9 (202) 53.2 (255) 47.1 (104) 45.4 (264) 50.4 (297) 47.9 (561) Secondary (n) 37.4 (176) 23.8 (114) 36.2 (80) 31.6 (184) 31.6 (186) 31.6 (370) Tertiary (n) 10.8 (51) 11.1 (53) 9.5 (21) 11.5 (73) 8.8 (52) 10.7 (125) Altitude of residence Highland (n) 27.2 (137) 32.8 (178) 41.7 (108) 53.7 (227) 46.3 196) 32.1 (423) Middle belt (n) 42.5 (214) 38.7 (215) 23.9 (62) 44.4 (218) 55.6 (273) 37.2 (491) Lowland (n) 30.4 (153) 29.3 (163) 34.4 (89) 51.1 (207) 48.9 (198) 30.7 (405) Clinical Fever prevalence (n) 8.3 (42) 9.5 (53) 6.6 (17) 8.1 (53) 8.8 (59) 8.5 (112) Malaria parasite prevalence (n) 36.7 (185) α 39.4 (219) α 29.3 (76) α 36.0 (235) 36.7 (245) 36.4 (480) Asymptomatic malaria parasite prevalence (n) 34.0 (164) β 36.9 (197) β 28.0 (71) β 33.6 (211) 34.4 (221) 34.0 (432) Sub microscopic infection prevalence (n) 28.7 (47) γ 51.3 (79) γ 60.5 (49) γ 46.9 (91) 40.8 (84) 43.8 (175) Malarial anaemia prevalence (n) 29.4 (148) ε 28.4 (158) ε 11.2 (29) ε 25.8 (168) 25.0 (167) 25.4 (335) α significant difference with age (χ 2 = 7.651 P = 0.021) β significant difference with age (χ 2 = 6.130 P = 0.047) γ significant difference with age (χ 2 = 27.358 P < 0.001) ε significant difference with age (χ 2 = 34.428 P < 0.001) Fever = axillary temperature ≥ 37.5ºC Asymptomatic malaria = malaria parasite positive without fever or history of it. Malaria anaemia = malaria parasite positive + Hb < 11g/dL. Asymptomatic malaria prevalence by altitude The prevalence of asymptomatic falciparum malaria among the 1271 children without fever varied with altitude. The overall prevalence in the low, middle belt and high lands was 44.6%, 25.2% and 34.1%. respectively and the difference was statistically significant (χ 2 = 35.980, P < 0.001) (Fig. 2). In the lowland, asymptomatic malaria was significantly highest (χ 2 = 6.651, P = 0.036) in children aged 5‒9 years (52.2%) old while, in the middle belt it was significantly highest (χ 2 = 7.007, P = 0.03) in children < 5 years (29.5%) when compared with their respective counterparts. No significant difference with age was observed in highlands even though the prevalence was highest in children 5–9 years old (37.4%). On the other hand, while children < 5 years in the low, middle belt and high lands had similar prevalence of asymptomatic malaria, those 5–9 years (52.2%) and 10–14 years (39.5%) resident in the lowlands, had the highest prevalence and the difference was significant (χ 2 = 28.830, P < 0.001 and χ 2 = 12.720, P = 0.002, respectively). As shown in Fig. 2, asymptomatic malaria prevalence among the sexes was comparable within the low and high lands but statistically different in the middle belt (χ 2 = 5.157, P = 0.023) where, females had higher prevalence (29.3%) than males (20.2%). Conversely, significantly higher (χ 2 = 32.251, P < 0.001 and χ 2 = 8.896, P = 0.012) prevalence was observed in males (46.5%) and females (42.6%) in the lowland when compared with those in the middle belt and highland, respectively. Malaria parasite density and category The geometric mean parasite density (GMPD) was significantly higher (P < 0.001) in children residing in the lowland (449 parasites/ µL of blood) when compared with those in the middle belt and highland as shown in Table 2 . Children < 5 years old in the lowland and middle belt had a significantly higher (P = 0.024 and P = 0.003) GMPD (538 and 224 parasites/ µL of blood), respectively, when compared with the older children. Although not significant GMPD decreased with an increase in age in the high lands. With respect to sex, the GMPD/ µL of blood in children residing in the middle belt was significantly higher (P = 0.025) in males (218) than females (187) while the higher values observed in males than females in the low (465) and high lands (385) were not significantly different. However, the GMPD/ µL of blood in males (465) and females (434) was significantly higher (P < 0.001) in the lowland when compared with the other altitudinal sites (Table 2 ). Table 2 Malaria parasite density in the different age groups and sex at different altitudes Parameter Altitude P value Lowland (range) GMPD/ µL of blood Middlebelt (range) GMPD/ µL of blood Highland (range) GMPD/ µL of blood Age < 5 538 (104–11520) 224 (82–1162) 399 (107–27060) < 0.001 a 5–9 456 (100–10920) 158 (70–1054) 379 (102–25546) < 0.001 a 10–14 320 (100–5740) 142 (82–363) 321 (102–3080) 0.078 P value 0.024* a 0.003** a 0.736 - Sex Male 465 (104–11520) 218 (70–1162) 385 (102 − 27060) 0.001 a Female 434 (100–10920) 172 (80–1122) 360 (102–7200) < 0.001 a Total 449 (100–11520) 187 (70–1162) 374 (102–27060) < 0.001 a P- value 0.563 0.025* b 0.728 - *statistically significant at P < 0.05 ** statistically significant at P < 0.01 *** statistically significant at P < 0.001. a Difference in GMPD in the different altitude and age groups determined by Kruskal–Wallis test b Difference in GMPD in the different sex determined by Mann–Whitney U test The prevalence of low, moderate and high parasitaemia in the study population were 84.2% (401/476), 12.4% (59/476) and 3.4% (16/476). As shown in Fig. 3, the prevalence of low, moderate and high malaria parasitaemia was significantly different (P < 0.001) in children from the different altitudes, with the low parasite density category being the most prevalent in all the three settings. Sub-microscopic infection prevalence and altitude Overall, the prevalence of sub-microscopic malaria parasitaemia with respect to altitude was highest in children in the highland (66.7%) and lowest in the lowland (29.2%). With respect to age related differences and altitude, among children < 5 years, those resident in middle belt had the highest sub-microscopic malaria parasite prevalence (34.1%). On the other hand, the 5–9 and 10–14 years old, resident in highland had significantly higher (P < 0.001) prevalence (87.2% and 81.8% respectively) than those in the other altitudinal sites. Moreover, males and female’s resident in the highlands had the highest prevalence of sub-microscopic infection (75.4% and 58.7%), compared to the other altitudinal sites at P < 0.001 and P = 0.002, respectively as shown in Table 3 . Table 3 Sub-microscopic malaria parasite prevalence in relation to age and sex stratified by altitude Parameter Altitude χ 2 ; P Highland % (n) Middle belt % (n) Lowland % (n) Age (years) < 5 40 30.0 (12) 82 34.1 (28) 42 16.7 (7) 4.197; 0.123 5–9 47 87.2 (41) 59 40.7 (24) 50 30.0 (15) 36.036; <0.001*** 10–14 33 81.8 (27) 19 42.1 (8) 28 46.4 (13) 11.229; 0.004** χ 2 P 36.556 < 0.001*** 0.820 0.664 7.232 0.027* - Sex Male 57 75.4 (43) 78 44.9 (35) 59 22.0 (13) 33.418, 0.001*** Female 63 58.7 (37) 82 30.5 (25) 61 36.1 (22) 12.564; 0.002** Total 120 66.7 (80) 160 37.5 (60) 120 29.2 (35) 38.519, 0.001*** χ 2 P 3.759 0.053 3.529 0.060 2.858 0.91 - * statistically significant at P < 0.05** statistically significant at P < 0.01*** statistically significant at P < 0.001 Anaemia prevalence and its severity The overall prevalence of anaemia was 62.3%. No significant differences were observed with sex and febrile status while, the prevalence of anaemia decreased significantly (P < 0.001) with an increase in age with youngest age group having a prevalence of 73.8%. The occurrence of anaemia was significantly higher in children from the middle belt (72.7%), those with asymptomatic (68.1%) and sub-microscopic (78.3%) Plasmodium infection than their respective equal (Table 5 ). Relating to the severity of anaemia, children aged < 5 years had the highest prevalence of severe (7.8%) and moderate (58.8%) anaemia while mild anaemia was most common in those 10‒14 years old (53.4%) and the difference was statistically significant at P < 0.001. Significantly (P < 0.001 and P = 0.006), moderate anaemia was the most occurring form of anaemia in children negative for asymptomatic malaria (56.7%) and those positive for sub-microscopic infection (64.2%), respectively, as shown in Table 4 . Table 4 Prevalence and severity of anaemia as affected by altitude, age, sex, asymptomatic malaria, sub microscopic infection and febrile status Variable Category No. examined Anaemia prevalence Anaemia severity prevalence No. examined Severe %(n) Moderate %(n) Mild %(n) Altitude Lowland 423 54.6 (221) 221 3.2 (7) 54.3 (120) 42.5 (94) Middle belt 405 72.7 (357) 357 3.9 (14) 54.1 (193) 42.0 (150) Highland 491 57.7 (244) 244 7.8 (19) 53.7 (131) 38.5 (94) χ 2 P 36.804, < 0.001*** 6.828, 0.145 Sex Male 652 62.4 (407) 407 54.4 (22) 54.3 (221) 40.3 (164) Female 667 62.2 (415) 415 4.3 (18) 53.7 (223) 41.9 (174) χ 2 P. 0.006 0.939 0.627 0.731 Age group (Years) < 5 503 73.8 (371) 371 7.8 (29) 58.8 (218) 33.4 (124) 5–9 557 62.5 (348) 348 2.3 (8) 52.0 (181) 45.7 (159) 10–14 259 39.8 (103) 103 2.9 (3) 43.7 (45) 53.4 (55) χ 2 P 84.121 < 0.001*** 26.885 < 0.001*** Asymptomatic malaria status Positive 432 68.1 (294) 294 4.1 (12) 50.0 (147) 45.9 (135) Negative 839 58.0 (487) 487 5.3 (26) 56.7 (276) 38.0 (185) χ 2 P 12.062 < 0.001*** 84.121 < 0.001*** Sub-microscopic status Positive 175 78.3 (137) 137 4.4 (6) 64.2 (88) 31.4 (43) Negative 225 43.1 (97) 97 6.2 (6) 43.3 (42) 50.5 (49) χ 2 P 50.167 < 0.001*** 10.127 < 0.006** Febrile status Febrile 112 67.0 (75) 75 2.7 (2) 62.7 (47) 34.7 (26) Afebrile 1207 61.9 (747) 747 5.1 (38) 53.1 (397) 41.8 (312) χ 2 P 1.124 < 0.289 2.800 0.247 ** statistically significant at P < 0.01 *** statistically significant at P < 0.001. Sub-microscopic infection and haematological indices The mean haematological parameters were comparable between children with and without sub microscopic infection except for the mean Hb levels, haematocrit (Hct), RBC (red blood cell) and platelet (Plt) counts, mean corpuscular haemoglobin concentration (MCHC) and red cell distribution–coefficient of variation (RDW-CV). Children with sub microscopic infection had a significantly lower mean Hb concentration (9.86 ± 1.7 g/dL), RBC (4.48 ± 1.1 x 10 12 /L) and Plt (280.83 ± 112.62) counts, Hct (31.92%) and MCHC (31.33 ± 4.74 g/L) than their negative counterparts as shown in Table 5 . On the other hand, the mean RDW-CV% (15.19 ± 3.3) was significantly higher (P < 0.001) in children with sub microscopic infection than those negative. Table 5 A comparison of mean haematological values in children positive for sub-microscopic infection and those negative Variable Sub microscopic status N Mean (SD) t-test 95% CI of difference P value WBC x 10 9 /L Pos 175 7.55 (2.87) 0.22 -0.46 - -0.58 Neg 225 7.48 (2.40) 0.824 Hb (g/dL) Pos 175 9.86 (1.65) -6.87 -1.69 - -0.94 Neg 225 11.18 (2.07) < 0.001*** RBC x 10 12 /L Pos 175 4.48 (1.05) -4.61 -0.76 - -0.31 Neg 225 5.01 (1.22) < 0.001*** Hct (%) Pos 175 31.92 (7.16) 3.33 -4.31 - -1.11 Neg 225 33.63 (8.74) < 0.001*** MCV (fl) Pos 175 72.58 (8.84) 1.40 -0.45 - -2.68 Neg 225 71.46 (7.10) 0.163 MCH (pg) Pos 175 34.16 (3.36) 2.15 -1.14 - -0.3 Neg 225 36.68 (3.83) 0.253 MCHC (g/L) Pos 175 31.33 (4.74) -2.11 -21.64 - -21.63 Neg 225 32.45 (5.64) 0.035 RDW-CV% Pos 175 15.19 (3.29) 3.24 0.38 - -1.56 Neg 225 14.21 (2.71) < 0.001*** Plt x 10 9 /L Pos 175 280.63 (112.62) -2.66 − 48.61 - -0.84 Neg 225 305.36 (126.32) 0.049* POS: positive, Neg: negative, * Statistically significant at P < 0.05*** statistically significant at P < 0.001 Risks factors of sub microscopic Plasmodium infection The logistic regression model with sub-microscopic infection status as dependent variable and altitude, age, gender, marital status, ITN usage, fever, fever within a month, anaemia and water source as independent variable, demonstrated that children from highlands (P = < 0.001), those between 5‒9 years (P = < 0.001) and 10‒14 years (P = < 0.001), those who didn’t use ITN (P = 0.04) and anaemic children (P = < 0.001) were more likely to have sub-microscopic malaria parasite infection. The odds of carrying sub-microscopic infection is presented in Table 6 . Children from highlands, those 5‒9 years and between 10‒14 years of age, who didn’t use ITN and anaemic as well were 1.8, 3, 8, 1.69 and 9 times more likely to carry sub-microscopic Plasmodium infection than their counterparts. Table 6 Logistic regression model examining factors associated with sub microscopic Plasmodium falciparum infection in the study population Variables N Sub-microscopic infection prevalence (n) Bivariate logistic regression Multivariate logistic regression COR (95% CI) P value AOR P Value Altitude Lowland 120 29.2 (35) Reference Reference Middle belt 160 37.5 (60) 1.46 (0.88–2.42) 0.15 0.52 (0.25–1.08) 0.08 Highland 120 66.7 (80) 4.86 (2.81–8.39) < 0.001*** 1.76 (0.86–3.60) 0.13 Age group (Years) < 5 165 28.5 (47) Reference Reference 5–9 154 51.3 (79) 2.64 (1.66–4.20) < 0.001*** 3.13 (1.77–5.56) < 0.001*** 10–14 81 60.5 (49) 3.84 (2.20–6.72) < 0.001*** 8.18 (3.91–17.20) < 0.001*** Gender Male 195 47.2 (92) Reference - Female 205 40.5 (83) 0.76 (0.51–1.13) 0.18 0.74 (0.45–1.20) 0.22 Marital status Married 293 40.6 (119) Reference - Single 97 51.5 (50) 1.56 (0.98–2.47) 0.06 1.67 (0.94–2.96) 0.08 Use of ITN Yes 221 35.7 (79) Reference - No 179 53.6 (96) 2.08 (1.39–3.11) < 0.001*** 1.69 (1.01–2.81) 0.04* Fever Yes 28 32.1 (9) Reference No 372 44.6 (166) 1.7 (0.75–3.86) 0.20 2.21 (0.77–6.40) 0.14 Fever within a month No fever 272 42.6 (116) Reference - - Fever 128 46.1 (59) 1.15 (0.75–1.76) 0.52 - - Anaemia No 166 22.9 (38) Reference Yes 234 58.5 (137) 4.76 (3.05–7.43) < 0.001*** 9.01 (4.51–17.99) < 0.001*** Malnourished No 271 42.8 (116) Reference - - - Yes 129 45.7 (59) 1.13 (0.74–1.72) 0.58 - - Water source Close 357 42.6 (152) Reference - Reference - Open 43 53.5 (23) 1.55 (0.82–2.93) 0.18 1.28 (0.59–2.75) 0.53 Stunting No 309 41.7 (129) Reference Yes 91 50.5 (46) 1.43 (0.89–2.28) 0.14 1.54 (0.85–2.80) 0.15 AOR: adjusted odd ratio, COR: crude odd ratio, *Statistically significant at P < 0.05, *** statistically significant at P < 0.001. Discussion Considerable progress has been made in the past years in reducing malaria morbidity and mortality in Africa, with Cameroon inclusive, largely due to interventions such as LLIN and use of artemisinin-based combination therapy [ 21 , 31 ]. Detailed assessments of parasite carriage by conventional diagnostics alongside molecular investigation have uncovered that a considerable proportion of malaria infections is undetected by routine microscopy [ 32 ]. In settings where recent malaria control efforts have been successful, and across various endemicities, sub-microscopic infections frequently outnumber microscopically detectable infections [ 5 , 16 , 33 ]. Although high levels of asymptomatic and sub-microscopic infection occur in many different settings [ 19 , 33 – 35 ], studies on their clinical significance are still lacking. This cross-sectional study examines the influence of asymptomatic and sub-microscopic P. falciparum infection on anaemia and haematological indices as public health problems in children ≤ 14 years across low, middle belt and highland altitudes in the Mount Cameroon area. Findings from the study suggests that children < 5years and 5–9 years in the middle belt and lowland respectively, are the most affected by the malaria parasite and therefore constitute sensitive groups for monitoring changes in malaria burden using microscopy in the Mount Cameroon area. Case management which is one of the current surveillance methods in the country focus more on the < 5 years age group, although asymptomatic malaria parasite which is also higher among the 5–9 years age group may greatly contribute to transmission. Consequently, health education and treatment should not only target vulnerable groups (< 5 years and pregnant women) but all the age groups. The prevalence and density of asymptomatic malaria parasitaemia with respect to age and sex were significantly different across the different altitudinal sites. This result is not surprising because several studies have reported that in Cameroon, malaria burden and transmission intensity are heterogeneous with spatial and temporal variations between altitudes and geographical areas, with prevalence rates varying from one area to another [ 4 ]. Although the prevalence of asymptomatic malaria parasite was comparable between males and females, the density was however higher in males than in females among middle belt dwellers. This is in line with an earlier study by Kimbi et al . [ 36 ] and Sumbele et al . [ 21 ]. In addition, the effect of sex on the outcome of P. falciparum infection has previously been reported in other parts of Africa [ 37 , 38 ]. Hormonal differences between the sexes may also be a contributing factor to the difference in malaria parasite prevalence. Cernetich et al . [ 39 ] showed that synthesis of testosterone by males suppresses antiplasmodial immune response, whereas production of oestrogen augments antiplasmodial immune response. The present study is the first large-scale description of sub-microscopic malaria parasite prevalence among children in three communities in the Mount Cameroon area using the nested PCR method. The overall sub-microscopic malaria parasitaemia of 43.8% was observed in microscopic negative slides by PCR in the study population. In line with other studies, Okell et al . [ 15 ] reported that the proportion of sub-microscopic infections is inversely correlated with slide prevalence and parasite density on the global level. Bousema et al . [ 5 ] reported that individuals with sub-microscopic malaria parasite are accountable for maintaining Plasmodium species between transmission season, since they are a major reservoir. Findings from the study indicated that the proportion of sub-microscopic infection in the communities were significantly associated with age, as older children had an increased chance of being carriers of sub-microscopic infection compared with those younger. This is consistent with reports from other studies from Uganda [ 40 ], Kenya [ 41 ], India [ 42 ] and Ethiopia [ 43 ] who reported that older children do not easily develop symptomatic malaria upon infection both because they tolerate parasite densities better without developing fever and because they are at lower risk to develop high parasite densities. Age is a key factor that correlates positively with protective immunity in malaria-endemic areas. It has been reported that parasitaemia in older age groups is lower than the detection limits of conventional malaria diagnostic tools, which therefore fail to detect parasitaemia [ 44 ]. The importance of the sub-microscopic parasite pool rests on the understanding that sub-microscopic infections can transmit malaria [ 45 ], although the minimum parasite density necessary for transmission is unknown. Worthy of note in the Mount Cameroon area, sub-microscopic Plasmodium infections in older children may be an important source of the local transmission of the parasite. In addition, the unusual significantly higher GMPD observed in children < 10 years living in the highlands than those in the middle belt is also of concern especially as the climatic conditions in the highlands are considered unfavourable for the development of the vector and transmission of the parasite. The prevalence of sub-microscopic infection was highest in the highland dwellers than lowland with children in the highlands having a lower malaria prevalence by microscopy when compared with their lowland counterparts. This observation support findings of other studies [ 14 , 46 ] which suggests that the burden of sub-microscopic infections is highly heterogeneous across different locations. Although several hypotheses could account for this, one possible explanation might be differences in the extent of parasite genetic diversity between settings [ 47 – 49 ]. In low transmission settings, repeated exposure to a limited number of strains might lead to rapid development of protective immunity against those strains. Individuals in these settings would then be expected to have, on average, a higher proportion of infected sub-microscopic population. By contrast, in high transmission settings, higher circulating parasite genetic diversity would mean that individuals are more frequently infected with strains they have not previously encountered. However, in contrast, a recent characterisation of sub-microscopic malaria carriage at three Ugandan sites with varied transmission intensity revealed little change in the extent and size of the sub-microscopic reservoir across the transmission gradient at the sub-national level [ 13 ]. In addition to altitudinal effect that may affect transmission dynamics, findings from the study revealed non-users of ITN were 2 folds more likely to carry sub-microscopic infection. This observation supports the findings of other studies that proper use of ITN significantly reduces malaria morbidity and mortality [ 2 , 50 ]. It has been reported that sub-microscopic and asymptomatic infections go undetected and untreated with little or no clinical manifestation in many malaria endemic communities [ 51 ]. However, findings from this study demonstrated that these infections are associated with anaemia as well a decrease in some red cell indices and platelet counts. Anaemic children were 9 times more likely to carry sub-microscopic infection when compared to non-anaemic children, demonstrating the clinical relevance of sub-microscopic infection. The result agrees with studies by Rek et al . [ 13 ] and De Mast et al . [ 35 ] who also suggested an association between sub-microscopic malaria infection and anaemia. Anaemia is multifactorial and observations from this study enriches the body of evidence suggesting the detrimental clinical consequences of parasitaemia of any density [ 17 , 33 ]. The high prevalence of anaemia (62.3%) in children less than or equal to 14 years among the population in this area highlights anaemia as a severe public health problem in malaria endemic communities. The association between malaria parasitaemia and anaemia is well established in previous studies [ 26 , 36 , 52 – 54 ]. Malaria parasitaemia causes devastation of parasitized and non-parasitized red blood cells hence reducing haemoglobin levels leading to anaemia. The higher proportion of anaemia in the younger age group is in line with previous studies that anaemia due to malaria is more severe in younger children in areas of intense transmission [ 55 , 56 ]. Children in this age group are more vulnerable to infection with malaria than others with severe and potentially fatal complications. Sub-microscopic Plasmodium infection in the study was associated with lower Hb, Hct, RBC count as well as MCHC as confirmed by the decrease in their mean values in those positive. It is most likely that sub-microscopic Plasmodium infection would have exacerbated the reduction in the red cell indices as asymptomatic parasitaemia and protracted malaria infections have been associated with a marked reduction in Hb concentration and with a clinically significant RBC destruction [ 57 ] indicating that parasitological cure is necessary for haematological recovery [ 58 ]. Findings revealed reduction in platelet count in children with sub-microscopic Plasmodium infection. The association of platelet count and malaria has previously been described [ 59 ]. However, the reduction did not culminate in thrombocytopaenia which is the reduction in platelet count below the normal range that has been postulated as a marker of Plasmodium infection. Thrombocytopaenia seems to occur through peripheral destruction [ 60 ], excessive removal of platelet by spleen pooling [ 61 ] as well as platelet consumption by the process of disseminated intravascular coagulopathy. Also, immune-mediated destruction of circulating platelets has been postulated as a cause of thrombocytopaenia [ 62 ]. While the findings reported have implications for the control and elimination of malaria in the Mount Cameroon area it could have a wider applicability in other regions with similar altitudinal ranges and environmental conditions. The study is however not without limitation, the study design does not allow the assessment of causality between sub microscopic parasitaemia and anaemia. Conclusions The significant heterogeneity in the burden of asymptomatic and sub-microscopic Plasmodium infection in addition to its corollary on haematological variables among children in the different attitudinal sites of the Mount Cameroon Region accentuate the need for strategic context specific planning of malaria control and preventative measures. While proper case management continues to be a focus of control efforts, novel strategies are also needed to target the asymptomatic and sub-microscopic parasite reservoirs alongside the consequences on anaemia and haematological indices among children in endemic regions. This information is priceless to use the limited resources in a cost-effective way to appropriately implement management. Abbreviations AOR: adjusted odd ratio; asl: above sea level; ACT: artemisinin-based combination therapy; CI: confidence interval; COR: crude odd ratio; DBS: dried blood spot; DNA: deoxyribonucleic acid; EDTA: ethylenediaminetetraacetate; GMPD: geometric mean parasite density; Hb: haemoglobin; Hct: haematocrit; ITNs: insecticide-treated bed nets; LLINs: long-lasting insecticidal nets; MA; malaria anaemia; MCH: mean corpuscular haemoglobin; MCHC: mean corpuscular haemoglobin concentration; MCV: mean corpuscular volume; OR: odd ratio; PCR: polymerase chain reaction; Plt: platelet; RBC: red blood cell; SD: standard deviations; RDW-CV; red cell distribution–coefficient of variation; WHO: World Health Organization; Declarations Ethical considerations and administrative approval The study was approved by the Institutional Review Board hosted by the Faculty of Health Sciences, University of Buea (2017/004/UB/FHS/IRB) following administrative clearance from the South West Regional Delegation of Public Health, Cameroon. Informed consent statement Written informed consent/assent forms were given or read and explained to parents or caregivers of the children at presentation. The purpose and benefits of the study as well as the amount of blood to be collected from each child were clearly stated in the information sheet and consent/assent forms, respectively. Only participants who gave written and/or verbal consent or assent documented by the investigator took part in the study. Participation was strictly voluntary, and parents or caregivers were free at any point in time to stop the participation of the child/children in the study. Consent for publication Not applicable. Availability of data and materials All datasets on which the conclusions of the research rely are presented in this paper. However, data is available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding This work was supported by Taif University Researchers Supporting Program (project number: TURSP-2020/153), Taif University, Saudi Arabia who had no role in the design of the study, collection, analysis, and interpretation of data as well as writing of the manuscript. Authors’ contributions IUNS conceived, designed and supervised the study, participated in data analysis and interpretation and was a major contributor to the write-up of the manuscript; RNT participated in data collection, laboratory analysis, analysed and interpreted the data and wrote a draft of the manuscript; GAN, SMS, MNM, RAS, CMS participated in data collection, and laboratory analysis; SMG, GEB, KFA participated in interpretation and revision of the manuscript; HKK participated in the study design, supervision and revision of the manuscript. All authors read and approved the final manuscript. Acknowledgments The authors appreciate the support and cooperation of the parents and guardians of the children in Tole, Dibanda and Batoke community, the health personnel and laboratory technicians who took part in the study. References World Health Organization. World Malaria Report. Geneva: World Health Organisation, 2020. ISBN 978-92-4-001579-1 Fokam EB, Kindzeka GF, Ngimuh L, Dzi KT, Wanji S. Determination of the predictive factors of long-lasting insecticide-treated net ownership and utilisation in the Bamenda Health District of Cameroon. BMC Public Health . 2017; 17(1): 263. Teh RN, Sumbele IUN, Meduke DN, Ojong ST, Kimbi HK: Malaria parasitaemia, anaemia and malnutrition in children less than 15 years residing in different altitudes along the slope of Mount Cameroon: prevalence, intensity and risk factors. Malar J. 2018; 17:336. Eyong EEJ, Kengne-Ouafo AJ, Chounna PW, Datchoua-Poutcheu FR, Wanji S. Altitudinal variation in the parasitological and entomological indices of malaria around Mount Cameroon, South West Region of Cameroon. J Parasitol Vector Biol . 2016; 8(8): 74-85. Bousema T, Okell L, Felger I, Drakeley C. Asymptomatic malaria infections: detectability, transmissibility and public health relevance. Nat Rev Microbiol . 2014; 12(12): 833. Galatas B, Bassat Q, Mayor A. Malaria parasites in the asymptomatic: looking for the hay in the haystack. Trends Parasitolol . 2016; 32(4): 296-308. World Health Organization. WHO malaria terminology. Geneva: World Health Organisation, 2016. https://www.who.int./malaria/publications/atoz/malaria-terminology/en/ . Accessed 05 March 2021. Lindblade KA, Steinhardt L, Samuels A, Kachur S P, Slutsker L. The silent threat: asymptomatic parasitemia and malaria transmission. Expert Rev Anti-Infect Ther . 2013; 11(6): 623-639. Kimbi H, Keka F, Nyabeyeu H, Ajeagah H, Tonga C, Lum E, et al. An update of asymptomatic falciparum malaria in school children in Muea, Southwest Cameroon. J Bacteriol Parasitol . 2012; 3(154): 2. Nzobo BJ, Ngasala BE Kihamia, CM. Prevalence of asymptomatic malaria infection and use of different malaria control measures among primary school children in Morogoro Municipality, Tanzania. Malar J. 2015; 14(1): 491. Kimbi H, Ajeagah H, Keka F, Lum E, Nyabeyeu H, Tonga C. Asymptomatic malaria in school children and evaluation of the performance characteristics of the Partec Cyscope® in the Mount Cameroon Region. J Bacteriol Parasitol . 2012; 3(153): 2. Gouagna L, Okech B, Kabiru E, Killeen G, Obare P, Ombonya S, et al. Infectivity of Plasmodium falciparum gametocytes in patients attending rural health centres in western Kenya. East Afr Med J . 2003; 80(12): 627-634. Rek J, Katrak S, Obasi H, Nayebare P, Katureebe A, Kakande E, et al. Characterizing microscopic and sub microscopic malaria parasitaemia at three sites with varied transmission intensity in Uganda. Malar J . 2016; 15(1): 470. Tadesse FG, van den Hoogen L, Lanke K, Schildkraut J, Tetteh K, Aseffa A, et al. The shape of the iceberg: quantification of sub microscopic Plasmodium falciparum and Plasmodium vivax parasitaemia and gametocytaemia in five low endemic settings in Ethiopia. Malar J. 2017; 16(1): 99. Okell LC, Bousema T, Griffin JT, Ouédraogo AL, Ghani AC, Drakeley CJ. Factors determining the occurrence of sub microscopic malaria infections and their relevance for control. Nat commun . 2012; 3: 1237. Imwong M, Stepniewska K, Tripura R, Peto TJ, Lwin KM, Vihokhern B, et al. Numerical distributions of parasite densities during asymptomatic malaria. Infect Dis . 2015; 213(8), 1322-1329. Cottrell G, Moussiliou A, Luty AJ, Cot M, Fievet N, Massougbodji A, et al. Sub microscopic Plasmodium falciparum infections are associated with maternal anemia, premature births, and low birth weight. Clin Infect Dis . 2015; 60(10): 1481-1488. Ladeia-Andrade S, Ferreira MU, de Carvalho ME, Curado I, Coura JR. Age-dependent acquisition of protective immunity to malaria in riverine populations of the Amazon Basin of Brazil. Am J Trop Med Hyg . 2009; 80(3): 452-459. Katrak S, Nayebare P, Rek J, Arinaitwe E, Nankabirwa JI, Kamya M, et al. Clinical consequences of sub microscopic malaria parasitaemia in Uganda. Malar J . 2018; 17 (1): 67. Sumbele IUN, Kimbi HK, Ndamukong-Nyanga JL, Nweboh M, Anchang-Kimbi JK, Lum E, et al. Malarial anaemia and anaemia severity in apparently healthy primary school children in urban and rural settings in the Mount Cameroon area: cross sectional survey. PloS One . 2015; 10(4), e0123549. Sumbele IUN, Ning TR, Bopda OS, Nkuo-Akenji T. Variation in malariometric and red cell indices in children in the Mount Cameroon area following enhanced malaria control measures: evidence from a repeated cross-sectional study. Malar J . 2014; 13(1), 334. Bowen HL. Impact of a mass media campaign on bed net use in Cameroon. Malar J . 2013; 12(1): 36. Teh RN, Sumbele IUN, Nkeudem GA, Meduke DN, Ojong ST, Kimbi HK. Concurrence of CareStart™ Malaria HRP2 RDT with microscopy in population screening for Plasmodium falciparum infection in the Mount Cameroon area: predictors for RDT positivity. Trop Med Health. 2019; 47:17. Ndamukong-Nyanga JL, Kimbi HK, Sumbele IUN, Nana Y, Bertek SC, Ndamukong KJ, et al. A cross-sectional study on the influence of altitude and urbanisation on co-infection of malaria and soil-transmitted helminths in Fako Division, South West Cameroon. Int J Trop Dis and Health . 2015; 8 (4): 150-164. Bryan FJ. The Design and Analysis of Research Studies, UK. University of Otago, Cambridge University Press, 1992. Sumbele IUN, Sama SO, Kimbi HK, Taiwe GS. Malaria, moderate to severe anaemia, and malarial anaemia in children at presentation to hospital in the Mount Cameroon area: A cross-sectional study. Anemia , 2016; Article ID 5725634. Cheesbrough, M. District laboratory practice in tropical countries: Part1and2: Cambridge University Press. 2009. Kimbi HK, Nkesa SB, Ndamukong-Nyanga JL, Sumbele IUN, Atashili J, Atanga MB. Knowledge and perceptions towards malaria prevention among vulnerable groups in the Buea Health District, Cameroon. BMC Public Health , 2014; 14(1): 883. Baidjoe A, Stone W, Ploemen I, Shagari S, Grignard L, Osoti V, et al. Combined DNA extraction and antibody elution from filter papers for the assessment of malaria transmission intensity in epidemiological studies. Malar J . 2013; 12(1): 272. Johnston SP, Pieniazek NJ, Xayavong MV, Slemenda SB, Wilkin PP, da Silva AJ. PCR as a confirmatory technique for laboratory diagnosis of malaria. J Clin Microbiol . 2006; 44(3):1087-1089. Bhatt S, Weiss D, Cameron E, Bisanzio D, Mappin B, Dalrymple U, et al. The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015. 2015; 526(7572):207. Wu L, van den Hoogen LL, Slater H, Walker PG, Ghani AC, Drakeley CJ, et al. Comparison of diagnostics for the detection of asymptomatic Plasmodium falciparum infections to inform control and elimination strategies. Nat . 2015;528(7580):S86. Chen I, Clarke SE, Gosling R, Hamainza B, Killeen G, Magill A, et al. “Asymptomatic” malaria: a chronic and debilitating infection that should be treated. PLoS Med . 2016;13(1):e1001942. Baum E, Sattabongkot J, Sirichausinthop J, Kiattibutr K, Jain A, Taghavian O, et al. Common asymptomatic and sub microscopic malaria infections in western Thailand revealed in longitudinal molecular and serological studies: a challenge to malaria elimination. Malar J . 2016; 15(1): 1-15. De Mast Q, Brouwers J, Syafruddin D, Bousema T, Baidjoe AY, de Groot PG, et al. Is asymptomatic malaria really asymptomatic? Hematological, vascular and inflammatory effects of asymptomatic malaria parasitemia. J Infect . 2015;71(5):587-96. Kimbi H, Nana Y, Sumbele I, Anchang-Kimbi J, Lum E, Tonga C et al. Environmental factors and preventive methods against malaria parasite prevalence in rural Bomaka and urban Molyko, Southwest Cameroon. J Bacteriol Parasitol . 2013;4(162):4172. Kepha S, Nikolay B, Nuwaha F, Mwandawiro CS, Nankabirwa J, Ndibazza J, et al. Plasmodium falciparum parasitaemia and clinical malaria among school children living in a high transmission setting in western Kenya. Malar J . 2016; 15(1), 1-13. Sarpong N, Owusu-Dabo E, Kreuels B, Fobil JN, Segbaya S, Amoyaw F, et al. Prevalence of malaria parasitaemia in school children from two districts of Ghana earmarked for indoor residual spraying: a cross-sectional study. Malar J . 2015; 14(1), 1-7. Cernetich A, Gaver LS, Jedlicka AE, Klein PW, Kumar N, Scott AL. Involvement of gonadal steroids and gamma interferon in sex differences in response to blood stage malaria infection . Infect Immunol . 2006; 74 (6): 3190-3203. Rodriguez-Barraquer I, Arinaitwe E, Jagannathan P, Kamya MR, Rosenthal PJ, Rek J, et al. Quantification of anti-parasite and anti-disease immunity to malaria as a function of age and exposure. Elife . 2018;7:e35832. Baliraine FN, Afrane YA, Amenya DA, Bonizzoni M, Menge DM, Zhou G, et al. High prevalence of asymptomatic Plasmodium falciparum infections in a highland area of western Kenya: a cohort study . J Infect Dis. 2009;200(1):66-74. Ganguly S, Saha P, Guha SK, Biswas A, Das S, Kundu PK, et al. High prevalence of asymptomatic malaria in a tribal population in eastern India. J Clin Microbiol. 2013;51(5):1439-44. Golassa L, Baliraine FN, Enweji N, Erko B, Swedberg G, Aseffa A. Microscopic and molecular evidence of the presence of asymptomatic Plasmodium falciparum and Plasmodium vivax infections in an area with low, seasonal and unstable malaria transmission in Ethiopia. BMC Infect Dis. 2015;15(1):310. Golassa L, Enweji N, Erko B, Aseffa A, Swedberg G. Detection of a substantial number of sub-microscopic Plasmodium falciparum infections by polymerase chain reaction: a potential threat to malaria control and diagnosis in Ethiopia. Mal J . 2013;12(1):352. Mosha JF, Sturrock HJ, Greenhouse B, Greenwood B, Sutherland CJ, Gadalla N, et al. Epidemiology of subpatent Plasmodium falciparum infection: implications for detection of hotspots with imperfect diagnostics. Mal J . 2013;12(1):221. Idris ZM, Chan CW, Kongere J, Gitaka J, Logedi J, Omar A, et al. High and heterogeneous prevalence of asymptomatic and sub-microscopic malaria infections on islands in Lake Victoria, Kenya. Sci Rep . 2016, 6:36958. Volkman SK, Neafsey DE, Schaffner SF, Park DJ, Wirth DF. Harnessing genomics and genome biology to understand malaria biology. Nat Rev Genet . 2012;13(5):315. Walk J, Reuling IJ, Behet MC, Meerstein-Kessel L, Graumans W, van Gemert G-J, et al. Modest heterologous protection after Plasmodium falciparum sporozoite immunization: a double-blind randomized controlled clinical trial. BMC Med . 2017;15(1):168. Elliott SR, Kuns RD, Good MF. Heterologous immunity in the absence of variant-specific antibodies after exposure to sub patent infection with blood-stage malaria. Infect Immun . 2005; 73(4):2478-2485. Lengeler C. Insecticide-treated bed nets and curtains for preventing malaria. Cochrane Database of Sys Rev . 2004; (2):1-46. Lin JT, Saunders DL, Meshnick SR. The role of sub microscopic parasitemia in malaria transmission: what is the evidence? Trends in Parasitol , 2014; 30(4): 183-190. Achidi EA, Apinjoh TO, Anchang-Kimbi JK, Mugri RN, Ngwai AN, Yafi CN. Severe and uncomplicated falciparum malaria in children from three regions and three ethnic groups in Cameroon: prospective study. Malar J . 2012;11(1):215. Apinjoh TO, Anchang-Kimbi JK, Mugri RN, Tangoh DA, Nyingchu RV, Chi HF, et al. The effect of insecticide treated nets (ITNs) on Plasmodium falciparum infection in rural and semi urban communities in the South West Region of Cameroon. PLoS One . 2015;10(2):e0116300. Kateera F, Mens PF, Hakizimana E, Ingabire CM, Muragijemariya L, Karinda P, et al. Malaria parasite carriage and risk determinants in a rural population: a malariometric survey in Rwanda. Malar J. 2015; 14(1):16. Asoba GN, Sumbele IUN, Anchang-Kimbi JK, Metuge S, Teh RN. Influence of infant feeding practices on the occurrence of malnutrition, malaria and anaemia in children ≤5 years in the Mount Cameroon area: A cross sectional study. PLoS One. 2019; 14(7): e0219386. Udoh E, Oyo-Ita A, Eyong K, Oringanje C, Oduwole O, Okebe J, et al. Malariometric indices among Nigerian children in rural setting. Malar Res Treat . 2013;716805. Price RN, Simpson JA, Nosten F, Luxemburger C, Hkirjaroen L, ter Kuile F, et al. Factors contributing to anemia after uncomplicated falciparum malaria. Am J Trop Med Hyg . 2001; 65(5):614-22. Ngole SIU, Theresa N-A, Moses S, Thomas N, Manka NE, Titanji V. Haematological changes and recovery associated with treated and untreated Plasmodium falciparum infection in children in the Mount Cameroon Region. Journal of Clinical Medicine and Research . 2010; 2(9): 143-151. Njunda AL, Ngouadjeu DT, Nsagha D, Nyanjoh EM, Kwenti T, Assob NJ. Haematological profile of children with malaria in Kumba Health District, South West Region Cameroon. Afr J Integrated Health . 2016, 6(2). Ladhani S, Lowe B, Cole AO, Kowuondo K, Newton CR. Changes in white blood cells and platelets in children with falciparum malaria: relationship to disease outcome. Br J Haematol . 2002; 119(3):839-847. Skudowitz R, Katz J, Lurie A, Levin J, Metz J. Mechanisms of thrombocytopenia in malignant tertian malaria. Br Med J . 1973;2(5865):515-8. Pain A, Ferguson DJ, Kai O, Urban BC, Lowe B, Marsh K, et al. Platelet-mediated clumping of Plasmodium falciparum -infected erythrocytes is a common adhesive phenotype and is associated with severe malaria. Proc Nati Acad Sci . 2001; 98(4):1805-10. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Major Revision 05 Jul, 2021 Review # 1 received at journal 09 Jun, 2021 Reviewer # 2 agreed at journal 23 May, 2021 Reviewer # 1 agreed at journal 23 May, 2021 Reviewers invited by journal 10 Mar, 2021 Editor invited by journal 09 Mar, 2021 Editor assigned by journal 08 Mar, 2021 Submission checks completed at journal 08 Mar, 2021 First submitted to journal 08 Mar, 2021 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-310174","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research","associatedPublications":[],"authors":[{"id":16088060,"identity":"4d364b72-74d6-4fa5-bd9f-725bf09a54a6","order_by":0,"name":"Irene Ule Ngole sumbele","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3ElEQVRIiWNgGAWjYHACNgaGAgYefjADApiJ0GLAwCPZQKoWBoMDxGqRn5Gd9uCDgY2M8Y3kZw8+VDDI8zPwGBvg02JwI3e74QyDNB6zG2nmhjPOMBjObOAxTsCrRSJ3mzSPwWGglgQzad42hgSDAzzGB/A7DKjlj8F/HuMZ6d+I08JwA6gF6HceA4kchC34HXbm7XbDHoNkHokzb8okZ5yRMJzZzFaM1/vy7bnbHvyosLPnb0/fJvGhwkaen715swReh8GBANg1EkREJBzwHyBa6SgYBaNgFIwwAAAMK0BStNGCUgAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0003-2607-8845","institution":"University of Buea","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Irene","middleName":"Ule Ngole","lastName":"sumbele","suffix":""},{"id":16088061,"identity":"6cdecdb0-0dc6-4e52-b899-194d53ed4fc4","order_by":1,"name":"Rene Ning Teh","email":"","orcid":"","institution":"University of Buea","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Rene","middleName":"Ning","lastName":"Teh","suffix":""},{"id":16088062,"identity":"242ccc7a-a7ce-45bc-ba9c-46e9519a0e5e","order_by":2,"name":"Gillian Asoba Nkeudem","email":"","orcid":"","institution":"University of Buea","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Gillian","middleName":"Asoba","lastName":"Nkeudem","suffix":""},{"id":16088063,"identity":"76e8c435-6482-4ff5-99a5-9118874c973a","order_by":3,"name":"Sorelle Mekachie Sandie","email":"","orcid":"","institution":"University of Buea","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Sorelle","middleName":"Mekachie","lastName":"Sandie","suffix":""},{"id":16088064,"identity":"44a498a3-2194-4997-8529-faa861116ded","order_by":4,"name":"Marcel Nyuylam Moyeh","email":"","orcid":"","institution":"University of Buea","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Marcel","middleName":"Nyuylam","lastName":"Moyeh","suffix":""},{"id":16088065,"identity":"79269356-a544-4624-aa22-759b63e671f8","order_by":5,"name":"Robert Adamou Shey","email":"","orcid":"","institution":"University of Buea","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Robert","middleName":"Adamou","lastName":"Shey","suffix":""},{"id":16088066,"identity":"77d8d947-3c28-4ff4-9c41-f6da9e3fc269","order_by":6,"name":"Cabirou Mounchili Shintouo","email":"","orcid":"","institution":"University of Buea","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Cabirou","middleName":"Mounchili","lastName":"Shintouo","suffix":""},{"id":16088067,"identity":"ba7b6a66-a2ff-468c-b857-fc8a0f05378a","order_by":7,"name":"Stephen Mbigha Ghogomu","email":"","orcid":"","institution":"University of Buea","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Stephen","middleName":"Mbigha","lastName":"Ghogomu","suffix":""},{"id":16088068,"identity":"725ec135-6790-4939-bbb9-46d0c903da74","order_by":8,"name":"Gaber El-Saber Batiha","email":"","orcid":"","institution":"Damanhour University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Gaber","middleName":"El-Saber","lastName":"Batiha","suffix":""},{"id":16088069,"identity":"b4298376-458d-4399-9edb-bca8bc694951","order_by":9,"name":"Khalaf F Alsharif","email":"","orcid":"","institution":"Taif University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Khalaf","middleName":"F","lastName":"Alsharif","suffix":""},{"id":16088070,"identity":"1b521b79-809c-4cc5-971d-e5d81747b413","order_by":10,"name":"Helen Kuokuo Kimbi","email":"","orcid":"","institution":"University of Bamenda","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Helen","middleName":"Kuokuo","lastName":"Kimbi","suffix":""}],"badges":[],"createdAt":"2021-03-08 14:13:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-310174/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-310174/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":7038352,"identity":"439c828b-5e88-4a6a-afda-e5175ae26283","added_by":"auto","created_at":"2021-03-16 22:59:32","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":108198,"visible":true,"origin":"","legend":"Location of the study sites in the Mount Cameroon area, Fako Division, South West Region, Cameroon. Note: The designations employed and the presentation of the material on this map do not imply the expression of any opinion whatsoever on the part of Research Square concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. This map has been provided by the authors.","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-310174/v1/e93a8cb4a5bbf0744fbee6f1.jpg"},{"id":7038166,"identity":"182ced45-ab74-4ba2-979b-9cebc5dbad2c","added_by":"auto","created_at":"2021-03-16 22:56:32","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":41385,"visible":true,"origin":"","legend":"Effect of age and sex on asymptomatic malaria prevalence stratified by altitude in the study population","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-310174/v1/03fb954460902eaf5416f59a.jpg"},{"id":7038353,"identity":"663cbb17-64ad-4c30-8329-0e12ffcb82fd","added_by":"auto","created_at":"2021-03-16 22:59:32","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":39769,"visible":true,"origin":"","legend":"Prevalence of malaria parasite density category by altitudinal site","description":"","filename":"Fig3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-310174/v1/bd1cdeb6c24b984586f5ed55.jpg"},{"id":15672050,"identity":"1da851d9-ef7b-4402-a06e-d11f96d80bc8","added_by":"auto","created_at":"2021-11-18 14:09:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":827935,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-310174/v1/16c35503-932a-4955-8220-6c494f5cbb24.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003eAsymptomatic and Sub-microscopic \u003cem\u003ePlasmodium Falciparum\u003c/em\u003e Infection in Children in the Mount Cameroon Area: a Cross-sectional Study on Altitudinal Influence, Haematological Parameters and Risk Factors\u003c/p\u003e","fulltext":[{"header":"Background","content":" \u003cp\u003eGlobally, malaria is still a public health concern, although the death cases have steadily reduced from 736000 in 2000 to 409000 deaths in 2019. Cameroon accounts for 3% of this number [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], even with the recommended world health organization (WHO) control measures put in place [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In some malaria endemic areas, particularly Cameroon, where the disease burden is diverse, variations between altitudes and geographical areas [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] may necessitate a strategic control measure. Falciparum malaria continues to negatively impact human life and in malaria-endemic countries, many \u003cem\u003ePlasmodium falciparum\u003c/em\u003e infections manifest through various outcomes ranging from asymptomatic infection to the complicated disease, depending on the parasite density [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAsymptomatic malaria is defined by the WHO as the presence of asexual parasites in blood, without symptoms of illness [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Other studies defined asymptomatic malaria as the existence of malarial parasitaemia of any density in blood without any symptoms in individuals who have not received recent antimalarial treatment in a given population [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. This definition includes early detection of rising parasitaemia or any density of parasitised red blood cell (RBC) that is not enough to trigger a fever response [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSeveral studies in the central and East part of Africa have reported great numbers of asymptomatic malaria in endemic communities [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. In some of these communities, asymptomatic malaria parasite carriers represent a persistent pool for maintaining the life cycle and transmission of the \u003cem\u003ePlasmodium\u003c/em\u003e species by the anopheline vector [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Also, Gouagna \u003cem\u003eet al\u003c/em\u003e. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] reported a higher susceptibility of the malaria parasite among asymptomatic carriers when compared to the symptomatic one\u0026rsquo;s.\u003c/p\u003e \u003cp\u003eSub-microscopic infections are present across different settings and populations [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Okell \u003cem\u003eet al\u003c/em\u003e. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] reported that the prevalence of sub-microscopic infections is inversely correlated with slide prevalence and parasite density on the global level. Several reports in low transmission settings have also suggested higher proportions of sub-microscopic infections when compared to microscopically detectable infections particularly in settings where recent malaria control efforts have been successful [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. This may not only be true in low transmission settings but may also be true in highly endemic communities, where a large proportion of sub patent infections may cause a partial non-sterilizing malaria immunity. Thus, it is necessary to uncover the extent of sub-microscopic infection in a high malaria transmission setting such as the Mount Cameroon area.\u003c/p\u003e \u003cp\u003eThe existence of a significant sub-microscopic infection prevalence in an otherwise asymptomatic, microscopically negative population in Ethiopia [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] highlights that malaria infections can continue in a community even in the absence of illness. Nevertheless, although rarely causative agent of severe, acute symptoms, sub-microscopic malaria has been associated with several adverse outcomes during pregnancy [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], as well as mild anaemia [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] and various other symptoms (coughing, vomiting, jaundice etc.) in children under 10 years [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] in low endemic areas. However, little is known on its association with altitude and haematological indices especially in areas with moderate to high endemicities.\u003c/p\u003e \u003cp\u003eThe Mount Cameroon Region represents a meso-hyperendemic setting and malaria epidemiology is highly heterogeneous as seen in many other parts of the country [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. This region has experienced a 57.2% malaria parasitaemia decline in confirmed malaria cases between 2006 and 2013 [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] mainly attributed to implementation of artemisinin-based combination therapy (ACT) and the wide scale distribution of long-lasting insecticide-treated nets [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. In 2011, Cameroon distributed over eight million long-lasting insecticidal nets (LLINs) throughout the country (22). The second nationwide distribution was carried out in 2016 and distributed about 12\u0026nbsp;million LLINs were distributed. Yet, the disease prevalence is still a public health concern and it remains unclear if this stability in endemicity over the years is associated with asymptomatic or sub-microscopic infections. However, there is no documented study relating the epidemiological characteristics of asymptomatic and sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection and their effects on haematological variables among children living in the different altitudinal sites along the Mount Cameroon area. Hence, determining the prevalence and association with haematological variables in this malaria endemic setting will be fundamental for a strategic control planning and subsequently elimination.\u003c/p\u003e "},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003eStudy area and participants\u003c/h2\u003e\n\u003cp\u003eThe study was carried out in Batoke (Limbe), Dibanda (Buea) and Tole (Buea), which are three semi-rural communities along different altitudinal ranges in the Mount Cameroon area, as shown in Fig.\u0026nbsp;1. The sites were classified as lowlands (\u0026lt;\u0026thinsp;200 m above sea level (asl)), middle belt (200\u0026ndash;600 m asl) and highlands (\u0026gt;\u0026thinsp;600 m asl). The coordinates of Batoke range from altitude 8m asl, latitude 04\u0026deg;01.364\u0026prime; N, longitude 009\u0026deg;05.971\u0026prime; E to 47m, 04\u0026deg;02.039\u0026prime; N and 009\u0026deg;05.808\u0026prime; E; Dibanda from altitude 358m asl, latitude 04\u0026deg;06.447\u0026prime; N, longitude 009\u0026deg;18.725\u0026prime; E to 400m asl, 04\u0026deg;07.179\u0026prime; N and 009\u0026deg;18.464\u0026prime; E and Tole is located between 627m asl, latitude 04\u0026deg;07.057\u0026prime;N, longitude 009\u0026deg;15.178\u0026prime;E and 630m asl, latitude 04\u0026deg;6.906\u0026prime;N, longitude 09\u0026deg;14.434\u0026prime;E. These three study sites have been described in detail by Teh \u003cem\u003eet al\u003c/em\u003e. [\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eThe work was conducted among pre- and school aged children of both sexes between 6 months and 14 years old, who granted assent and whose parents/caregivers consented to participate in the study. The inclusion and exclusion criteria of this study were revised according to Teh \u003cem\u003eet al.\u003c/em\u003e [\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n\u003ch2\u003eStudy design\u003c/h2\u003e\n\u003cp\u003eThis cross-sectional community-based study was conducted between the months of July 2017 and May 2018. Participants were invited for data collection in each community by their local chiefs and coordination was organised by the head/leader of a block within a neighbourhood (\u0026ldquo;quarter head\u0026rdquo;) of the various communities. Potential participants were reminded of the collection dates per block by the head/leader of the block. At the start of the study in each site, the parents, guardians and children were educated on the study protocol and the benefits of participation highlighted at their various neighbourhoods using an information sheet. Upon obtaining informed consent/assent from the parents/care givers, the study team proceeded with the collection of samples at specific identified collect sites.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n\u003ch2\u003eSample size and sampling techniques\u003c/h2\u003e\n\u003cp\u003eThe sample size for each study altitude was calculated using the 66.2 % prevalence of malaria in children in the study area [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e]. Sample size was determined using the formula n\u0026thinsp;=\u0026thinsp;Z\u003csup\u003e2\u003c/sup\u003epq/d\u003csup\u003e2\u003c/sup\u003e [\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e] where n\u0026thinsp;=\u0026thinsp;the sample size required, z\u0026thinsp;=\u0026thinsp;1.96: which is the standard normal deviate (for a 95% confidence interval, CI), p\u0026thinsp;=\u0026thinsp;66.2%: proportion of malaria prevalence, q\u0026thinsp;=\u0026thinsp;1 - p: proportion of malaria negative children and d\u0026thinsp;=\u0026thinsp;acceptable error willing to be committed. The minimum sample size was estimated as n\u0026thinsp;=\u0026thinsp;344 for each site. Considering a possible participation of more than one child per family, loss of samples due to blood clotting and incomplete data entry, the sample size was adjusted by 10% to a minimum of 379.\u003c/p\u003e\n\u003cp\u003eA multistage cluster sampling method was used to obtain the required sample. In the first stage, all the communities in the Mount Cameroon area were stratified into 3 zones namely lowland, Middlebelt and highland. One community was randomly selected from each zone namely, Tole (highland), Dibanda (middle belt) and Batoke (lowland). In the second stage, 21 clusters (quarters) were randomly selected from 31clusters within the three communities. Within the clusters, all the households with children\u0026thinsp;\u0026le;\u0026thinsp;14 years of age were selected. In a household where only one child within that age was present, the child was selected automatically. In a case where more than one child was present in a household, only one was randomly selected. A probability proportionate to size sampling method was used to select 400 random malaria negative samples from all the negative samples in the study population for the sub-microscopic studies.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n\u003ch2\u003eCollection of data\u003c/h2\u003e\n\u003cp\u003eSociodemographic data which included information on sex, age, literacy level of parents/caregivers and malaria preventive methods, as well as fever history of participants were collected using a structured questionnaire.\u003c/p\u003e\n\u003cp\u003eAxillary temperature was measured using an electronic thermometer with a febrile condition considered as temperature\u0026thinsp;\u0026ge;\u0026thinsp;37.5\u0026ordm;C [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n\u003ch2\u003eLaboratory methods\u003c/h2\u003e\n\u003cp\u003eThree to four (3\u0026ndash;4) millilitres (mL) of venous blood sample was collected from each child using sterile disposable syringes. Part of the blood sample was used to prepare thick and thin films on the same slide for the determination of the presence of malaria parasite by Giemsa-stain microscopy using standard methods [\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e]. Parasite densities were expressed as asexual parasites per \u0026micro;L with reference to the participant\u0026rsquo;s white blood cell count (WBC) and categorised as low, moderate, high and hyper parasitaemia [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eAlso, 50 \u0026micro;L of the EDTA blood sample was aliquoted onto a Whatman 3mm filter paper and dried overnight at room temperature. The dried blood spots (DBS) were used to determine sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection. Genomic deoxyribonucleic acid (DNA) was isolated from the DBS using chelex [\u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e]. Primary and nested polymerase chain reaction (PCR) assays were carried out for all genes. The primary PCR was carried out with a pair of \u003cem\u003ePlasmodium\u003c/em\u003e genus-specific primers (rPLU5- 5\u0026rsquo;CCTGTTGTTGCCTTAAACTTC3\u0026rsquo; and rPLUS6- 5\u0026rsquo;TTAAAATTGTTGCAGTTAAAACG3\u0026rsquo;) which amplified a 1100-base pair (bp) PCR product from the rRNA small subunit gene (18S rRNA) while the nested primers specific for \u003cem\u003eP. falciparum\u003c/em\u003e (rFAL1\u0026ndash;5\u0026rsquo;TTAAACTGGTTTGGGAAAACCAAATATATT3\u0026rsquo;) and rFal2\u0026ndash;5\u0026rsquo;ACACAATGAACTCAATCATGACTACCCGTC3\u0026rsquo;) were used, which amplified a 205-bp indicating a \u003cem\u003eP. falciparum\u003c/em\u003e infection [\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eFurthermore, an auto-haematology analyser (Urit-3300\u0026reg; analyser, Guangxi, China) was used to assess haematological parameters following the manufacturer\u0026rsquo;s instructions and the condition of anaemia was defined as haemoglobin level (Hb)\u0026thinsp;\u0026lt;\u0026thinsp;11g/dL of whole blood [\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n\u003ch2\u003eDefinitions and end points\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eSub-microscopic infection was defined as low-density blood-stage malaria parasite infection that was not detected by conventional microscopy but positive using PCR.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eAsymptomatic malaria parasitaemia was defined as the presence of \u003cem\u003ePlasmodium\u003c/em\u003e by microscopy and with an axillary temperature of \u0026lt;\u0026thinsp;37.5\u0026deg;C and no record of fever within the past 2 weeks.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eParasitaemia was categorised as low (\u0026lt;\u0026thinsp;1,000 parasites/\u0026micro;L blood), moderate (1,000‒4,999 parasites/ \u0026micro;L blood), high (5,000‒99,999 parasites/ \u0026micro;L blood), and hyper parasitaemia (\u0026ge;\u0026thinsp;100,000 \u0026micro;L) [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eAnaemia was defined as Hb\u0026thinsp;\u0026lt;\u0026thinsp;11.0 g/dL and further categorized as severe (Hb\u0026thinsp;\u0026lt;\u0026thinsp;7.0 g/dL), moderate (Hb between 7.0 and 10.0 g/dL), and mild (Hb between 10.1 and \u0026lt;\u0026thinsp;11 g/dL) [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eMalarial anaemia (MA) was defined as children with a malaria-positive smear for \u003cem\u003eP. falciparum\u003c/em\u003e parasitaemia (of any density) and Hb\u0026thinsp;\u0026lt;\u0026thinsp;11 g/dL.\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ul\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n\u003ch2\u003eStatistical analysis\u003c/h2\u003e\n\u003cp\u003eContinuous variables were summarized into means and standard deviations (SD) and categorical variables reported as frequencies and percentages, were used to evaluate the descriptive statistics. The differences in proportions were evaluated using Pearson\u0026rsquo;s Chi-Square (\u0026chi;\u003csup\u003e2\u003c/sup\u003e). Group means were compared using Kruskal Wallis and Mann-Whitney U Test. Parasite densities were log transformed before analysis. Associations between predictor variables and primary outcomes were assessed using both bivariate and multivariate logistic regression analysis. Odd ratios (ORs) and 95 % confidence intervals (CIs) were computed. Any covariate with a P value\u0026thinsp;\u0026lt;\u0026thinsp;0.2 in the bivariate analysis was subsequently included in the final multivariable logistic model. Significant levels were measured at 95% CI with the level of significance set at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05. Post entry and clean-up of data in Microsoft Excel 2016, analysis was performed using the IBM-Statistical Package for Social Sciences (IBM-SPSS) version 20 and Epi-info version 7.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n\u003ch2\u003eSocio\u0026ndash;Demographic and Clinical Characteristics of the Study Population\u003c/h2\u003e\n\u003cp\u003eA total of 1319 children with a mean (SD) age of 6.0 (3.5) years, residing at lowland (30.7%, 405), middle belt (37.2%, 491) and highland (32.1%, 423) in the Mount Cameroon area were evaluated. As shown in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, most of the parents/caregiver of the children had a primary (47.9%) and secondary (31.6%) level of education. The proportion of febrile children in the study population was 8.5% (112), with no significant differences in age and sex. The prevalence of malaria and malaria anaemia in the study population was 36.4% and 25.4%% respectively. Children between 5‒9 years had the highest occurrence of malaria (39.4%) at P\u0026thinsp;=\u0026thinsp;0.021 while those under 5 years had the highest occurrence malaria anaemia (29.4%) when compared with their contemporaries at P\u0026thinsp;\u0026lt;\u0026thinsp;0.001, respectively.\u003c/p\u003e\n\u003cp\u003eA complete clinical and laboratory data for a total of 1271 and 400 children were used to determine the prevalence of asymptomatic and sub-microscopic malaria infection, respectively. The prevalence of asymptomatic and sub-microscopic malaria infection in the study population was 34.0% and 48.3%, respectively. The prevalence of asymptomatic malaria was significantly highest (P\u0026thinsp;=\u0026thinsp;0.047) among the 5‒9 years age group (36.9%), while the 10\u0026ndash;14 years age group (60.5%) had the highest level of sub microscopic infection (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) when compared with the other age groups (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eDemographic, altitude and clinical characteristics of the participants by age and sex\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eParameter\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003eAge groups in years\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eSex\u003c/p\u003e\n\u003c/th\u003e\n\u003cth rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eTotal\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;5\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e5\u0026ndash;9\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e10\u0026ndash;14\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eMale\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eFemale\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e% (N)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e38.1 (503)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e42.2 (557)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e19.6 (259)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e49.4 (652)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e50.6 (667)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e100 (1319)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMean age (SD) in years\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2.5 (1.2)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6.7 (1.4)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11.5 (1.2)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6.3 (3.5)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5.9 (3.5)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6.0 (3.5)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMean haemoglobin (SD) level in g/dL\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e9.9 (2.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10.6 (1.7)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11.2 (1.7)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10.4 (1.8)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10.5 (1.9)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10.5 (1.8)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eEducational level of parent/caregiver\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNo formal (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8.9 (42)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11.9 (57)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e7.2 (16)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10.5 (61)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e9.2 (54)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e9.8 (115)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ePrimary (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e42.9 (202)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e53.2 (255)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e47.1 (104)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e45.4 (264)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e50.4 (297)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e47.9 (561)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eSecondary (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e37.4 (176)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e23.8 (114)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e36.2 (80)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e31.6 (184)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e31.6 (186)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e31.6 (370)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eTertiary (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10.8 (51)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11.1 (53)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e9.5 (21)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11.5 (73)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8.8 (52)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10.7 (125)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eAltitude of residence\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eHighland (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e27.2 (137)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e32.8 (178)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e41.7 (108)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e53.7 (227)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e46.3 196)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e32.1 (423)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMiddle belt (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e42.5 (214)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e38.7 (215)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e23.9 (62)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e44.4 (218)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e55.6 (273)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e37.2 (491)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eLowland (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e30.4 (153)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e29.3 (163)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e34.4 (89)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e51.1 (207)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e48.9 (198)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e30.7 (405)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eClinical\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eFever prevalence (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8.3 (42)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e9.5 (53)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6.6 (17)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8.1 (53)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8.8 (59)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8.5 (112)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMalaria parasite prevalence (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e36.7 (185)\u003csup\u003e\u0026alpha;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e39.4 (219)\u003csup\u003e\u0026alpha;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e29.3 (76)\u003csup\u003e\u0026alpha;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e36.0 (235)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e36.7 (245)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e36.4 (480)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eAsymptomatic malaria parasite prevalence (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e34.0 (164)\u003csup\u003e\u0026beta;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e36.9 (197)\u003csup\u003e\u0026beta;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e28.0 (71)\u003csup\u003e\u0026beta;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e33.6 (211)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e34.4 (221)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e34.0 (432)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eSub microscopic infection prevalence (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e28.7 (47)\u003csup\u003e\u0026gamma;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e51.3 (79)\u003csup\u003e\u0026gamma;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e60.5 (49)\u003csup\u003e\u0026gamma;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e46.9 (91)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e40.8 (84)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e43.8 (175)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMalarial anaemia prevalence (n)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e29.4 (148)\u003csup\u003e\u0026epsilon;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e28.4 (158)\u003csup\u003e\u0026epsilon;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11.2 (29)\u003csup\u003e\u0026epsilon;\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e25.8 (168)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e25.0 (167)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e25.4 (335)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\"\u003e\n\u003cp\u003e\u003csup\u003e\u0026alpha;\u003c/sup\u003e significant difference with age (\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;7.651 P\u0026thinsp;=\u0026thinsp;0.021)\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e\u0026beta;\u003c/sup\u003e\u0026nbsp;significant difference with age (\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;6.130 P\u0026thinsp;=\u0026thinsp;0.047)\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e\u0026gamma;\u003c/sup\u003e\u0026nbsp;significant difference with age (\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;27.358 P\u0026thinsp;\u0026lt;\u0026thinsp;0.001)\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e\u0026epsilon;\u003c/sup\u003e\u0026nbsp;significant difference with age (\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;34.428 P\u0026thinsp;\u0026lt;\u0026thinsp;0.001)\u003c/p\u003e\n\u003cp\u003eFever\u0026thinsp;=\u0026thinsp;axillary temperature\u0026thinsp;\u0026ge;\u0026thinsp;37.5\u0026ordm;C\u003c/p\u003e\n\u003cp\u003eAsymptomatic malaria\u0026thinsp;=\u0026thinsp;malaria parasite positive without fever or history of it.\u003c/p\u003e\n\u003cp\u003eMalaria anaemia\u0026thinsp;=\u0026thinsp;malaria parasite positive\u0026thinsp;+\u0026thinsp;Hb\u0026thinsp;\u0026lt;\u0026thinsp;11g/dL.\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n\u003ch2\u003eAsymptomatic malaria prevalence by altitude\u003c/h2\u003e\n\u003cp\u003eThe prevalence of asymptomatic falciparum malaria among the 1271 children without fever varied with altitude. The overall prevalence in the low, middle belt and high lands was 44.6%, 25.2% and 34.1%. respectively and the difference was statistically significant (\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;35.980, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) (Fig.\u0026nbsp;2). In the lowland, asymptomatic malaria was significantly highest (\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;6.651, P\u0026thinsp;=\u0026thinsp;0.036) in children aged 5‒9 years (52.2%) old while, in the middle belt it was significantly highest (\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;7.007, P\u0026thinsp;=\u0026thinsp;0.03) in children\u0026thinsp;\u0026lt;\u0026thinsp;5 years (29.5%) when compared with their respective counterparts. No significant difference with age was observed in highlands even though the prevalence was highest in children 5\u0026ndash;9 years old (37.4%). On the other hand, while children\u0026thinsp;\u0026lt;\u0026thinsp;5 years in the low, middle belt and high lands had similar prevalence of asymptomatic malaria, those 5\u0026ndash;9 years (52.2%) and 10\u0026ndash;14 years (39.5%) resident in the lowlands, had the highest prevalence and the difference was significant (\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;28.830, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001 and \u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;12.720, P\u0026thinsp;=\u0026thinsp;0.002, respectively). As shown in Fig.\u0026nbsp;2, asymptomatic malaria prevalence among the sexes was comparable within the low and high lands but statistically different in the middle belt (\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;5.157, P\u0026thinsp;=\u0026thinsp;0.023) where, females had higher prevalence (29.3%) than males (20.2%). Conversely, significantly higher (\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;32.251, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001 and \u0026chi;\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;8.896, P\u0026thinsp;=\u0026thinsp;0.012) prevalence was observed in males (46.5%) and females (42.6%) in the lowland when compared with those in the middle belt and highland, respectively.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n\u003ch2\u003eMalaria parasite density and category\u003c/h2\u003e\n\u003cp\u003eThe geometric mean parasite density (GMPD) was significantly higher (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) in children residing in the lowland (449 parasites/ \u0026micro;L of blood) when compared with those in the middle belt and highland as shown in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e. Children\u0026thinsp;\u0026lt;\u0026thinsp;5 years old in the lowland and middle belt had a significantly higher (P\u0026thinsp;=\u0026thinsp;0.024 and P\u0026thinsp;=\u0026thinsp;0.003) GMPD (538 and 224 parasites/ \u0026micro;L of blood), respectively, when compared with the older children. Although not significant GMPD decreased with an increase in age in the high lands. With respect to sex, the GMPD/ \u0026micro;L of blood in children residing in the middle belt was significantly higher (P\u0026thinsp;=\u0026thinsp;0.025) in males (218) than females (187) while the higher values observed in males than females in the low (465) and high lands (385) were not significantly different. However, the GMPD/ \u0026micro;L of blood in males (465) and females (434) was significantly higher (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) in the lowland when compared with the other altitudinal sites (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eMalaria parasite density in the different age groups and sex at different altitudes\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth colspan=\"2\" rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eParameter\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003eAltitude\u003c/p\u003e\n\u003c/th\u003e\n\u003cth rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eP value\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eLowland (range)\u003c/p\u003e\n\u003cp\u003eGMPD/ \u0026micro;L of blood\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eMiddlebelt (range)\u003c/p\u003e\n\u003cp\u003eGMPD/ \u0026micro;L of blood\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eHighland (range)\u003c/p\u003e\n\u003cp\u003eGMPD/ \u0026micro;L of blood\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"3\" align=\"left\"\u003e\n\u003cp\u003eAge\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e538 (104\u0026ndash;11520)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e224 (82\u0026ndash;1162)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e399 (107\u0026ndash;27060)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5\u0026ndash;9\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e456 (100\u0026ndash;10920)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e158 (70\u0026ndash;1054)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e379 (102\u0026ndash;25546)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10\u0026ndash;14\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e320 (100\u0026ndash;5740)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e142 (82\u0026ndash;363)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e321 (102\u0026ndash;3080)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.078\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eP value\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.024*\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.003**\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.736\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eSex\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMale\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e465 (104\u0026ndash;11520)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e218 (70\u0026ndash;1162)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e385 (102 \u0026minus;\u0026thinsp;27060)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.001\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eFemale\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e434 (100\u0026ndash;10920)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e172 (80\u0026ndash;1122)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e360 (102\u0026ndash;7200)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt; 0.001\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eTotal\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e449 (100\u0026ndash;11520)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e187 (70\u0026ndash;1162)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e374 (102\u0026ndash;27060)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt; 0.001\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eP- value\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.563\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.025*\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.728\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"6\"\u003e*statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 ** statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.01 *** statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.001.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"6\"\u003e\u003csup\u003ea\u003c/sup\u003eDifference in GMPD in the different altitude and age groups determined by Kruskal\u0026ndash;Wallis test\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"6\"\u003e\u003csup\u003eb\u003c/sup\u003eDifference in GMPD in the different sex determined by Mann\u0026ndash;Whitney U test\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe prevalence of low, moderate and high parasitaemia in the study population were 84.2% (401/476), 12.4% (59/476) and 3.4% (16/476). As shown in Fig.\u0026nbsp;3, the prevalence of low, moderate and high malaria parasitaemia was significantly different (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) in children from the different altitudes, with the low parasite density category being the most prevalent in all the three settings.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n\u003ch2\u003eSub-microscopic infection prevalence and altitude\u003c/h2\u003e\n\u003cp\u003eOverall, the prevalence of sub-microscopic malaria parasitaemia with respect to altitude was highest in children in the highland (66.7%) and lowest in the lowland (29.2%). With respect to age related differences and altitude, among children\u0026thinsp;\u0026lt;\u0026thinsp;5 years, those resident in middle belt had the highest sub-microscopic malaria parasite prevalence (34.1%). On the other hand, the 5\u0026ndash;9 and 10\u0026ndash;14 years old, resident in highland had significantly higher (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) prevalence (87.2% and 81.8% respectively) than those in the other altitudinal sites. Moreover, males and female\u0026rsquo;s resident in the highlands had the highest prevalence of sub-microscopic infection (75.4% and 58.7%), compared to the other altitudinal sites at P\u0026thinsp;\u0026lt;\u0026thinsp;0.001 and P\u0026thinsp;=\u0026thinsp;0.002, respectively as shown in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab3\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eSub-microscopic malaria parasite prevalence in relation to age and sex stratified by altitude\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth colspan=\"2\" rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eParameter\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"6\" align=\"left\"\u003e\n\u003cp\u003eAltitude\u003c/p\u003e\n\u003c/th\u003e\n\u003cth rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u0026chi;\u003csup\u003e2\u003c/sup\u003e; P\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eHighland % (n)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eMiddle belt % (n)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eLowland % (n)\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"3\" align=\"left\"\u003e\n\u003cp\u003eAge\u003c/p\u003e\n\u003cp\u003e(years)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e40\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e30.0 (12)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e82\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e34.1 (28)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e42\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e16.7 (7)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4.197; 0.123\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5\u0026ndash;9\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e47\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e87.2 (41)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e59\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e40.7 (24)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e50\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e30.0 (15)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e36.036; \u0026lt;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10\u0026ndash;14\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e33\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e81.8 (27)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e19\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e42.1 (8)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e28\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e46.4 (13)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11.229; 0.004**\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eP\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e36.556\u003c/p\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e0.820\u003c/p\u003e\n\u003cp\u003e0.664\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e7.232\u003c/p\u003e\n\u003cp\u003e0.027*\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eSex\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMale\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e57\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e75.4 (43)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e78\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e44.9 (35)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e59\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e22.0 (13)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e33.418, 0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eFemale\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e63\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e58.7 (37)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e82\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e30.5 (25)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e61\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e36.1 (22)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e12.564; 0.002**\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eTotal\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e120\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e66.7 (80)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e160\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e37.5 (60)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e120\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e29.2 (35)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e38.519, 0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eP\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e3.759\u003c/p\u003e\n\u003cp\u003e0.053\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e3.529\u003c/p\u003e\n\u003cp\u003e0.060\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e2.858\u003c/p\u003e\n\u003cp\u003e0.91\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"9\"\u003e* statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05** statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.01*** statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\n\u003ch2\u003eAnaemia prevalence and its severity\u003c/h2\u003e\n\u003cp\u003eThe overall prevalence of anaemia was 62.3%. No significant differences were observed with sex and febrile status while, the prevalence of anaemia decreased significantly (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) with an increase in age with youngest age group having a prevalence of 73.8%. The occurrence of anaemia was significantly higher in children from the middle belt (72.7%), those with asymptomatic (68.1%) and sub-microscopic (78.3%) \u003cem\u003ePlasmodium\u003c/em\u003e infection than their respective equal (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e). Relating to the severity of anaemia, children aged\u0026thinsp;\u0026lt;\u0026thinsp;5 years had the highest prevalence of severe (7.8%) and moderate (58.8%) anaemia while mild anaemia was most common in those 10‒14 years old (53.4%) and the difference was statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.001. Significantly (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001 and P\u0026thinsp;=\u0026thinsp;0.006), moderate anaemia was the most occurring form of anaemia in children negative for asymptomatic malaria (56.7%) and those positive for sub-microscopic infection (64.2%), respectively, as shown in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab4\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003ePrevalence and severity of anaemia as affected by altitude, age, sex, asymptomatic malaria, sub microscopic infection and febrile status\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eVariable\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eCategory\u003c/p\u003e\n\u003c/th\u003e\n\u003cth rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eNo. examined\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eAnaemia prevalence\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"6\" align=\"left\"\u003e\n\u003cp\u003eAnaemia severity prevalence\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eNo. examined\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eSevere\u003c/p\u003e\n\u003cp\u003e%(n)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eModerate\u003c/p\u003e\n\u003cp\u003e%(n)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eMild\u003c/p\u003e\n\u003cp\u003e%(n)\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"3\" align=\"left\"\u003e\n\u003cp\u003eAltitude\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eLowland\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e423\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e54.6 (221)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e221\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e3.2 (7)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e54.3 (120)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e42.5 (94)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eMiddle belt\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e405\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e72.7 (357)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e357\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e3.9 (14)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e54.1 (193)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e42.0 (150)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eHighland\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e491\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e57.7 (244)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e244\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e7.8 (19)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e53.7 (131)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e38.5 (94)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eP\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e36.804,\u003c/p\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"6\" align=\"left\"\u003e\n\u003cp\u003e6.828,\u003c/p\u003e\n\u003cp\u003e0.145\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eSex\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eMale\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e652\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e62.4 (407)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e407\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e54.4 (22)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e54.3 (221)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e40.3 (164)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eFemale\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e667\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e62.2 (415)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e415\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4.3 (18)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e53.7 (223)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e41.9 (174)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eP.\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e0.006\u003c/p\u003e\n\u003cp\u003e0.939\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"6\" align=\"left\"\u003e\n\u003cp\u003e0.627\u003c/p\u003e\n\u003cp\u003e0.731\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"3\" align=\"left\"\u003e\n\u003cp\u003eAge group (Years)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e503\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e73.8 (371)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e371\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e7.8 (29)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e58.8 (218)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e33.4 (124)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e5\u0026ndash;9\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e557\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e62.5 (348)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e348\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2.3 (8)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e52.0 (181)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e45.7 (159)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e10\u0026ndash;14\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e259\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e39.8 (103)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e103\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2.9 (3)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e43.7 (45)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e53.4 (55)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eP\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e84.121\u003c/p\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"6\" align=\"left\"\u003e\n\u003cp\u003e26.885\u003c/p\u003e\n\u003cp\u003e\u0026lt; 0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eAsymptomatic malaria status\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003ePositive\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e432\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e68.1 (294)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e294\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4.1 (12)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e50.0 (147)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e45.9 (135)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eNegative\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e839\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e58.0 (487)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e487\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5.3 (26)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e56.7 (276)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e38.0 (185)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eP\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e12.062\u003c/p\u003e\n\u003cp\u003e\u0026lt; 0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"6\" align=\"left\"\u003e\n\u003cp\u003e84.121\u003c/p\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eSub-microscopic status\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003ePositive\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e175\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e78.3 (137)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e137\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4.4 (6)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e64.2 (88)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e31.4 (43)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eNegative\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e225\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e43.1 (97)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e97\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6.2 (6)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e43.3 (42)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e50.5 (49)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eP\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e50.167\u003c/p\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"6\" align=\"left\"\u003e\n\u003cp\u003e10.127\u003c/p\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.006**\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"2\" rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eFebrile status\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eFebrile\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e112\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e67.0 (75)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e75\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e2.7 (2)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e62.7 (47)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e34.7 (26)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eAfebrile\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e1207\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e61.9 (747)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e747\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e5.1 (38)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e53.1 (397)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e41.8 (312)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eP\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e1.124\u003c/p\u003e\n\u003cp\u003e\u0026lt; 0.289\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"6\" align=\"left\"\u003e\n\u003cp\u003e2.800\u003c/p\u003e\n\u003cp\u003e0.247\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"12\"\u003e** statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.01 *** statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.001.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\n\u003ch2\u003eSub-microscopic infection and haematological indices\u003c/h2\u003e\n\u003cp\u003eThe mean haematological parameters were comparable between children with and without sub microscopic infection except for the mean Hb levels, haematocrit (Hct), RBC (red blood cell) and platelet (Plt) counts, mean corpuscular haemoglobin concentration (MCHC) and red cell distribution\u0026ndash;coefficient of variation (RDW-CV). Children with sub microscopic infection had a significantly lower mean Hb concentration (9.86\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7 g/dL), RBC (4.48\u0026thinsp;\u0026plusmn;\u0026thinsp;1.1 x 10\u003csup\u003e12\u003c/sup\u003e/L) and Plt (280.83\u0026thinsp;\u0026plusmn;\u0026thinsp;112.62) counts, Hct (31.92%) and MCHC (31.33\u0026thinsp;\u0026plusmn;\u0026thinsp;4.74 g/L) than their negative counterparts as shown in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e. On the other hand, the mean RDW-CV% (15.19\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3) was significantly higher (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) in children with sub microscopic infection than those negative.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab5\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eA comparison of mean haematological values in children positive for sub-microscopic infection and those negative\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eVariable\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eSub microscopic status\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eN\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eMean (SD)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003et-test\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e95% CI of difference\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eP value\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eWBC x 10\u003csup\u003e9\u003c/sup\u003e/L\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ePos\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e175\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e7.55 (2.87)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.22\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e-0.46 - -0.58\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNeg\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e225\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e7.48 (2.40)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.824\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eHb (g/dL)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ePos\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e175\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e9.86 (1.65)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-6.87\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e-1.69 - -0.94\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNeg\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e225\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11.18 (2.07)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eRBC x 10\u003csup\u003e12\u003c/sup\u003e/L\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ePos\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e175\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4.48 (1.05)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-4.61\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e-0.76 - -0.31\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNeg\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e225\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5.01 (1.22)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eHct (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ePos\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e175\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e31.92 (7.16)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e3.33\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e-4.31 - -1.11\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNeg\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e225\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e33.63 (8.74)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eMCV (fl)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ePos\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e175\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e72.58 (8.84)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.40\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e-0.45 - -2.68\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNeg\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e225\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e71.46 (7.10)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.163\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eMCH (pg)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ePos\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e175\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e34.16 (3.36)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2.15\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e-1.14 - -0.3\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNeg\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e225\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e36.68 (3.83)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.253\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eMCHC (g/L)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ePos\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e175\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e31.33 (4.74)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-2.11\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e-21.64 - -21.63\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNeg\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e225\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e32.45 (5.64)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.035\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eRDW-CV%\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ePos\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e175\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e15.19 (3.29)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e3.24\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e0.38 - -1.56\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNeg\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e225\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e14.21 (2.71)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003ePlt x 10\u003csup\u003e9\u003c/sup\u003e/L\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ePos\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e175\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e280.63 (112.62)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-2.66\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u0026minus;\u0026thinsp;48.61 - -0.84\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNeg\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e225\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e305.36 (126.32)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.049*\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"6\"\u003ePOS: positive, Neg: negative, * Statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05*** statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003eRisks factors of sub microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection\u003c/h2\u003e\n\u003cp\u003eThe logistic regression model with sub-microscopic infection status as dependent variable and altitude, age, gender, marital status, ITN usage, fever, fever within a month, anaemia and water source as independent variable, demonstrated that children from highlands (P\u0026thinsp;=\u0026thinsp;\u0026lt;\u0026thinsp;0.001), those between 5‒9 years (P\u0026thinsp;=\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and 10‒14 years (P\u0026thinsp;=\u0026thinsp;\u0026lt;\u0026thinsp;0.001), those who didn\u0026rsquo;t use ITN (P\u0026thinsp;=\u0026thinsp;0.04) and anaemic children (P\u0026thinsp;=\u0026thinsp;\u0026lt;\u0026thinsp;0.001) were more likely to have sub-microscopic malaria parasite infection. The odds of carrying sub-microscopic infection is presented in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e. Children from highlands, those 5‒9 years and between 10‒14 years of age, who didn\u0026rsquo;t use ITN and anaemic as well were 1.8, 3, 8, 1.69 and 9 times more likely to carry sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection than their counterparts.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab6\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eLogistic regression model examining factors associated with sub microscopic \u003cem\u003ePlasmodium falciparum\u003c/em\u003e infection in the study population\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eVariables\u003c/p\u003e\n\u003c/th\u003e\n\u003cth rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eN\u003c/p\u003e\n\u003c/th\u003e\n\u003cth rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eSub-microscopic infection prevalence (n)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eBivariate logistic regression\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eMultivariate logistic regression\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eCOR (95% CI)\u003c/strong\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eP value\u003c/strong\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eAOR\u003c/strong\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eP Value\u003c/strong\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eAltitude\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eLowland\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e120\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e29.2 (35)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMiddle belt\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e160\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e37.5 (60)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.46 (0.88\u0026ndash;2.42)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.15\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.52 (0.25\u0026ndash;1.08)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.08\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eHighland\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e120\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e66.7 (80)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4.86 (2.81\u0026ndash;8.39)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.76 (0.86\u0026ndash;3.60)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.13\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eAge group (Years)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e165\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e28.5 (47)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5\u0026ndash;9\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e154\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e51.3 (79)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2.64 (1.66\u0026ndash;4.20)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e3.13 (1.77\u0026ndash;5.56)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10\u0026ndash;14\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e81\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e60.5 (49)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e3.84 (2.20\u0026ndash;6.72)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8.18 (3.91\u0026ndash;17.20)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eGender\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMale\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e195\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e47.2 (92)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eFemale\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e205\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e40.5 (83)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.76 (0.51\u0026ndash;1.13)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.18\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.74 (0.45\u0026ndash;1.20)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.22\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eMarital status\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMarried\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e293\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e40.6 (119)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eSingle\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e97\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e51.5 (50)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.56 (0.98\u0026ndash;2.47)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.06\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.67 (0.94\u0026ndash;2.96)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.08\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eUse of ITN\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eYes\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e221\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e35.7 (79)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNo\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e179\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e53.6 (96)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2.08 (1.39\u0026ndash;3.11)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.69 (1.01\u0026ndash;2.81)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.04*\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eFever\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eYes\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e28\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e32.1 (9)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNo\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e372\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e44.6 (166)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.7 (0.75\u0026ndash;3.86)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.20\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2.21 (0.77\u0026ndash;6.40)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.14\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eFever within a month\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNo fever\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e272\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e42.6 (116)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eFever\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e128\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e46.1 (59)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.15 (0.75\u0026ndash;1.76)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.52\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eAnaemia\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNo\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e166\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e22.9 (38)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eYes\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e234\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e58.5 (137)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4.76 (3.05\u0026ndash;7.43)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e9.01 (4.51\u0026ndash;17.99)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026lt;\u0026thinsp;0.001***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eMalnourished\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNo\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e271\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e42.8 (116)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eYes\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e129\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e45.7 (59)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.13 (0.74\u0026ndash;1.72)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.58\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eWater source\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eClose\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e357\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e42.6 (152)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eOpen\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e43\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e53.5 (23)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.55 (0.82\u0026ndash;2.93)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.18\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.28 (0.59\u0026ndash;2.75)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.53\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eStunting\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNo\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e309\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e41.7 (129)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eReference\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eYes\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e91\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e50.5 (46)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.43 (0.89\u0026ndash;2.28)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.14\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.54 (0.85\u0026ndash;2.80)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.15\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"7\"\u003eAOR: adjusted odd ratio, COR: crude odd ratio, *Statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, *** statistically significant at P\u0026thinsp;\u0026lt;\u0026thinsp;0.001.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eConsiderable progress has been made in the past years in reducing malaria morbidity and mortality in Africa, with Cameroon inclusive, largely due to interventions such as LLIN and use of artemisinin-based combination therapy [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e]. Detailed assessments of parasite carriage by conventional diagnostics alongside molecular investigation have uncovered that a considerable proportion of malaria infections is undetected by routine microscopy [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e]. In settings where recent malaria control efforts have been successful, and across various endemicities, sub-microscopic infections frequently outnumber microscopically detectable infections [\u003cspan class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e]. Although high levels of asymptomatic and sub-microscopic infection occur in many different settings [\u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e], studies on their clinical significance are still lacking. This cross-sectional study examines the influence of asymptomatic and sub-microscopic \u003cem\u003eP. falciparum\u003c/em\u003e infection on anaemia and haematological indices as public health problems in children\u0026thinsp;\u0026le;\u0026thinsp;14 years across low, middle belt and highland altitudes in the Mount Cameroon area.\u003c/p\u003e\n\u003cp\u003eFindings from the study suggests that children\u0026thinsp;\u0026lt;\u0026thinsp;5years and 5\u0026ndash;9 years in the middle belt and lowland respectively, are the most affected by the malaria parasite and therefore constitute sensitive groups for monitoring changes in malaria burden using microscopy in the Mount Cameroon area. Case management which is one of the current surveillance methods in the country focus more on the \u0026lt;\u0026thinsp;5 years age group, although asymptomatic malaria parasite which is also higher among the 5\u0026ndash;9 years age group may greatly contribute to transmission. Consequently, health education and treatment should not only target vulnerable groups (\u0026lt;\u0026thinsp;5 years and pregnant women) but all the age groups.\u003c/p\u003e\n\u003cp\u003eThe prevalence and density of asymptomatic malaria parasitaemia with respect to age and sex were significantly different across the different altitudinal sites. This result is not surprising because several studies have reported that in Cameroon, malaria burden and transmission intensity are heterogeneous with spatial and temporal variations between altitudes and geographical areas, with prevalence rates varying from one area to another [\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e]. Although the prevalence of asymptomatic malaria parasite was comparable between males and females, the density was however higher in males than in females among middle belt dwellers. This is in line with an earlier study by Kimbi \u003cem\u003eet al\u003c/em\u003e. [\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e] and Sumbele \u003cem\u003eet al\u003c/em\u003e. [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]. In addition, the effect of sex on the outcome of \u003cem\u003eP. falciparum\u003c/em\u003e infection has previously been reported in other parts of Africa [\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e]. Hormonal differences between the sexes may also be a contributing factor to the difference in malaria parasite prevalence. Cernetich \u003cem\u003eet al\u003c/em\u003e. [\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e] showed that synthesis of testosterone by males suppresses antiplasmodial immune response, whereas production of oestrogen augments antiplasmodial immune response.\u003c/p\u003e\n\u003cp\u003eThe present study is the first large-scale description of sub-microscopic malaria parasite prevalence among children in three communities in the Mount Cameroon area using the nested PCR method. The overall sub-microscopic malaria parasitaemia of 43.8% was observed in microscopic negative slides by PCR in the study population. In line with other studies, Okell \u003cem\u003eet al\u003c/em\u003e. [\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e] reported that the proportion of sub-microscopic infections is inversely correlated with slide prevalence and parasite density on the global level. Bousema \u003cem\u003eet al\u003c/em\u003e. [\u003cspan class=\"CitationRef\"\u003e5\u003c/span\u003e] reported that individuals with sub-microscopic malaria parasite are accountable for maintaining \u003cem\u003ePlasmodium\u003c/em\u003e species between transmission season, since they are a major reservoir.\u003c/p\u003e\n\u003cp\u003eFindings from the study indicated that the proportion of sub-microscopic infection in the communities were significantly associated with age, as older children had an increased chance of being carriers of sub-microscopic infection compared with those younger. This is consistent with reports from other studies from Uganda [\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e], Kenya [\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e], India [\u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e] and Ethiopia [\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e] who reported that older children do not easily develop symptomatic malaria upon infection both because they tolerate parasite densities better without developing fever and because they are at lower risk to develop high parasite densities. Age is a key factor that correlates positively with protective immunity in malaria-endemic areas. It has been reported that parasitaemia in older age groups is lower than the detection limits of conventional malaria diagnostic tools, which therefore fail to detect parasitaemia [\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eThe importance of the sub-microscopic parasite pool rests on the understanding that sub-microscopic infections can transmit malaria [\u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e], although the minimum parasite density necessary for transmission is unknown. Worthy of note in the Mount Cameroon area, sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infections in older children may be an important source of the local transmission of the parasite. In addition, the unusual significantly higher GMPD observed in children\u0026thinsp;\u0026lt;\u0026thinsp;10 years living in the highlands than those in the middle belt is also of concern especially as the climatic conditions in the highlands are considered unfavourable for the development of the vector and transmission of the parasite.\u003c/p\u003e\n\u003cp\u003eThe prevalence of sub-microscopic infection was highest in the highland dwellers than lowland with children in the highlands having a lower malaria prevalence by microscopy when compared with their lowland counterparts. This observation support findings of other studies [\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e46\u003c/span\u003e] which suggests that the burden of sub-microscopic infections is highly heterogeneous across different locations. Although several hypotheses could account for this, one possible explanation might be differences in the extent of parasite genetic diversity between settings [\u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e49\u003c/span\u003e]. In low transmission settings, repeated exposure to a limited number of strains might lead to rapid development of protective immunity against those strains. Individuals in these settings would then be expected to have, on average, a higher proportion of infected sub-microscopic population. By contrast, in high transmission settings, higher circulating parasite genetic diversity would mean that individuals are more frequently infected with strains they have not previously encountered. However, in contrast, a recent characterisation of sub-microscopic malaria carriage at three Ugandan sites with varied transmission intensity revealed little change in the extent and size of the sub-microscopic reservoir across the transmission gradient at the sub-national level [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eIn addition to altitudinal effect that may affect transmission dynamics, findings from the study revealed non-users of ITN were 2 folds more likely to carry sub-microscopic infection. This observation supports the findings of other studies that proper use of ITN significantly reduces malaria morbidity and mortality [\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e50\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eIt has been reported that sub-microscopic and asymptomatic infections go undetected and untreated with little or no clinical manifestation in many malaria endemic communities [\u003cspan class=\"CitationRef\"\u003e51\u003c/span\u003e]. However, findings from this study demonstrated that these infections are associated with anaemia as well a decrease in some red cell indices and platelet counts. Anaemic children were 9 times more likely to carry sub-microscopic infection when compared to non-anaemic children, demonstrating the clinical relevance of sub-microscopic infection. The result agrees with studies by Rek \u003cem\u003eet al\u003c/em\u003e. [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e] and De Mast \u003cem\u003eet al\u003c/em\u003e. [\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e] who also suggested an association between sub-microscopic malaria infection and anaemia. Anaemia is multifactorial and observations from this study enriches the body of evidence suggesting the detrimental clinical consequences of parasitaemia of any density [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eThe high prevalence of anaemia (62.3%) in children less than or equal to 14 years among the population in this area highlights anaemia as a severe public health problem in malaria endemic communities. The association between malaria parasitaemia and anaemia is well established in previous studies [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e54\u003c/span\u003e]. Malaria parasitaemia causes devastation of parasitized and non-parasitized red blood cells hence reducing haemoglobin levels leading to anaemia. The higher proportion of anaemia in the younger age group is in line with previous studies that anaemia due to malaria is more severe in younger children in areas of intense transmission [\u003cspan class=\"CitationRef\"\u003e55\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e56\u003c/span\u003e]. Children in this age group are more vulnerable to infection with malaria than others with severe and potentially fatal complications.\u003c/p\u003e\n\u003cp\u003eSub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection in the study was associated with lower Hb, Hct, RBC count as well as MCHC as confirmed by the decrease in their mean values in those positive. It is most likely that sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection would have exacerbated the reduction in the red cell indices as asymptomatic parasitaemia and protracted malaria infections have been associated with a marked reduction in Hb concentration and with a clinically significant RBC destruction [\u003cspan class=\"CitationRef\"\u003e57\u003c/span\u003e] indicating that parasitological cure is necessary for haematological recovery [\u003cspan class=\"CitationRef\"\u003e58\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eFindings revealed reduction in platelet count in children with sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection. The association of platelet count and malaria has previously been described [\u003cspan class=\"CitationRef\"\u003e59\u003c/span\u003e]. However, the reduction did not culminate in thrombocytopaenia which is the reduction in platelet count below the normal range that has been postulated as a marker of \u003cem\u003ePlasmodium\u003c/em\u003e infection. Thrombocytopaenia seems to occur through peripheral destruction [\u003cspan class=\"CitationRef\"\u003e60\u003c/span\u003e], excessive removal of platelet by spleen pooling [\u003cspan class=\"CitationRef\"\u003e61\u003c/span\u003e] as well as platelet consumption by the process of disseminated intravascular coagulopathy. Also, immune-mediated destruction of circulating platelets has been postulated as a cause of thrombocytopaenia [\u003cspan class=\"CitationRef\"\u003e62\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eWhile the findings reported have implications for the control and elimination of malaria in the Mount Cameroon area it could have a wider applicability in other regions with similar altitudinal ranges and environmental conditions. The study is however not without limitation, the study design does not allow the assessment of causality between sub microscopic parasitaemia and anaemia.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe significant heterogeneity in the burden of asymptomatic and sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection in addition to its corollary on haematological variables among children in the different attitudinal sites of the Mount Cameroon Region accentuate the need for strategic context specific planning of malaria control and preventative measures. While proper case management continues to be a focus of control efforts, novel strategies are also needed to target the asymptomatic and sub-microscopic parasite reservoirs alongside the consequences on anaemia and haematological indices among children in endemic regions. This information is priceless to use the limited resources in a cost-effective way to appropriately implement management.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eAOR: adjusted odd ratio; asl: above sea level; ACT: artemisinin-based combination therapy; CI: confidence interval; COR: crude odd ratio; DBS: dried blood spot; DNA: deoxyribonucleic acid; EDTA: ethylenediaminetetraacetate; GMPD: geometric mean parasite density; Hb: haemoglobin; Hct: haematocrit; ITNs: insecticide-treated bed nets; LLINs: long-lasting insecticidal nets; MA; malaria anaemia; MCH: mean corpuscular haemoglobin; MCHC: mean corpuscular haemoglobin concentration; MCV: mean corpuscular volume; OR: odd ratio; PCR: polymerase chain reaction; Plt: platelet; RBC: red blood cell; SD: standard deviations; RDW-CV; red cell distribution\u0026ndash;coefficient of variation; WHO: World Health Organization;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical considerations and administrative approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was approved by the Institutional Review Board hosted by the Faculty of Health Sciences, University of Buea (2017/004/UB/FHS/IRB) following administrative clearance from the South West Regional Delegation of Public Health, Cameroon.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed consent statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent/assent forms were given or read and explained to parents or caregivers of the children at presentation. The purpose and benefits of the study as well as the amount of blood to be collected from each child were clearly stated in the information sheet and consent/assent forms, respectively. Only participants who gave written and/or verbal consent or assent documented by the investigator took part in the study. Participation was strictly voluntary, and parents or caregivers were free at any point in time to stop the participation of the child/children in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll datasets on which the conclusions of the research rely are presented in this paper. However, data is available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by Taif University Researchers Supporting Program (project number: TURSP-2020/153), Taif University, Saudi Arabia who had no role in the design of the study, collection, analysis, and interpretation of data as well as writing of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIUNS conceived, designed and supervised the study, participated in data analysis and interpretation and was a major contributor to the write-up of the manuscript; RNT participated in data collection, laboratory analysis, analysed and interpreted the data and wrote a draft of the manuscript; GAN, SMS, MNM, RAS, CMS participated in data collection, and laboratory analysis; SMG, GEB, KFA participated in interpretation and revision of the manuscript; HKK participated in the study design, supervision and revision of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors appreciate the support and cooperation of the parents and guardians of the children in Tole, Dibanda and Batoke community, the health personnel and laboratory technicians who took part in the study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eWorld Health Organization. World Malaria Report. Geneva: World Health Organisation, 2020. ISBN 978-92-4-001579-1\u003c/li\u003e\n\u003cli\u003eFokam EB, Kindzeka GF, Ngimuh L, Dzi KT, Wanji S. Determination of the predictive factors of long-lasting insecticide-treated net ownership and utilisation in the Bamenda Health District of Cameroon. \u003cem\u003eBMC Public Health\u003c/em\u003e. 2017; 17(1): 263.\u003c/li\u003e\n\u003cli\u003eTeh RN, Sumbele IUN, Meduke DN, Ojong ST, Kimbi HK: Malaria parasitaemia, anaemia and malnutrition in children less than 15 years residing in different altitudes along the slope of Mount Cameroon: prevalence, intensity and risk factors. \u003cem\u003eMalar J. \u003c/em\u003e2018; 17:336.\u003c/li\u003e\n\u003cli\u003eEyong EEJ, Kengne-Ouafo AJ, Chounna PW, Datchoua-Poutcheu FR, Wanji S. Altitudinal variation in the parasitological and entomological indices of malaria around Mount Cameroon, South West Region of Cameroon. \u003cem\u003eJ Parasitol Vector Biol\u003c/em\u003e. 2016; 8(8): 74-85.\u003c/li\u003e\n\u003cli\u003eBousema T, Okell L, Felger I, Drakeley C. Asymptomatic malaria infections: detectability, transmissibility and public health relevance. \u003cem\u003eNat Rev Microbiol\u003c/em\u003e. 2014; 12(12): 833.\u003c/li\u003e\n\u003cli\u003eGalatas B, Bassat Q, Mayor A. Malaria parasites in the asymptomatic: looking for the hay in the haystack. \u003cem\u003eTrends Parasitolol\u003c/em\u003e. 2016; 32(4): 296-308.\u003c/li\u003e\n\u003cli\u003eWorld Health Organization. WHO malaria terminology. Geneva: World Health Organisation, 2016. \u003ca href=\"https://www.who.int./malaria/publications/atoz/malaria-terminology/en/\"\u003ehttps://www.who.int./malaria/publications/atoz/malaria-terminology/en/\u003c/a\u003e. Accessed 05 March 2021.\u003c/li\u003e\n\u003cli\u003eLindblade KA, Steinhardt L, Samuels A, Kachur S P, Slutsker L. The silent threat: asymptomatic parasitemia and malaria transmission. \u003cem\u003eExpert Rev Anti-Infect Ther\u003c/em\u003e. 2013; 11(6): 623-639.\u003c/li\u003e\n\u003cli\u003eKimbi H, Keka F, Nyabeyeu H, Ajeagah H, Tonga C, Lum E, et al. An update of asymptomatic falciparum malaria in school children in Muea, Southwest Cameroon. \u003cem\u003eJ Bacteriol Parasitol\u003c/em\u003e. 2012; 3(154): 2.\u003c/li\u003e\n\u003cli\u003eNzobo BJ, Ngasala BE Kihamia, CM. Prevalence of asymptomatic malaria infection and use of different malaria control measures among primary school children in Morogoro Municipality, Tanzania. \u003cem\u003eMalar J. \u003c/em\u003e2015; 14(1): 491.\u003c/li\u003e\n\u003cli\u003eKimbi H, Ajeagah H, Keka F, Lum E, Nyabeyeu H, Tonga C. Asymptomatic malaria in school children and evaluation of the performance characteristics of the Partec Cyscope\u0026reg; in the Mount Cameroon Region. \u003cem\u003eJ Bacteriol Parasitol\u003c/em\u003e. 2012; 3(153): 2.\u003c/li\u003e\n\u003cli\u003eGouagna L, Okech B, Kabiru E, Killeen G, Obare P, Ombonya S, et al. Infectivity of \u003cem\u003ePlasmodium falciparum\u003c/em\u003e gametocytes in patients attending rural health centres in western Kenya. \u003cem\u003eEast Afr Med J\u003c/em\u003e. 2003; 80(12): 627-634.\u003c/li\u003e\n\u003cli\u003eRek J, Katrak S, Obasi H, Nayebare P, Katureebe A, Kakande E, et al. Characterizing microscopic and sub microscopic malaria parasitaemia at three sites with varied transmission intensity in Uganda. \u003cem\u003eMalar J\u003c/em\u003e. 2016; 15(1): 470.\u003c/li\u003e\n\u003cli\u003eTadesse FG, van den Hoogen L, Lanke K, Schildkraut J, Tetteh K, Aseffa A, et al. The shape of the iceberg: quantification of sub microscopic \u003cem\u003ePlasmodium falciparum\u003c/em\u003e and \u003cem\u003ePlasmodium vivax\u003c/em\u003e parasitaemia and gametocytaemia in five low endemic settings in Ethiopia. \u003cem\u003eMalar J.\u003c/em\u003e 2017; 16(1): 99.\u003c/li\u003e\n\u003cli\u003eOkell LC, Bousema T, Griffin JT, Ou\u0026eacute;draogo AL, Ghani AC, Drakeley CJ. Factors determining the occurrence of sub microscopic malaria infections and their relevance for control. \u003cem\u003eNat commun\u003c/em\u003e. 2012; 3: 1237.\u003c/li\u003e\n\u003cli\u003eImwong M, Stepniewska K, Tripura R, Peto TJ, Lwin KM, Vihokhern B, et al. Numerical distributions of parasite densities during asymptomatic malaria. \u003cem\u003eInfect Dis\u003c/em\u003e. 2015; 213(8), 1322-1329.\u003c/li\u003e\n\u003cli\u003eCottrell G, Moussiliou A, Luty AJ, Cot M, Fievet N, Massougbodji A, et al. Sub microscopic \u003cem\u003ePlasmodium falciparum\u003c/em\u003e infections are associated with maternal anemia, premature births, and low birth weight. \u003cem\u003eClin Infect Dis\u003c/em\u003e. 2015; 60(10): 1481-1488.\u003c/li\u003e\n\u003cli\u003eLadeia-Andrade S, Ferreira MU, de Carvalho ME, Curado I, Coura JR. Age-dependent acquisition of protective immunity to malaria in riverine populations of the Amazon Basin of Brazil. \u003cem\u003eAm J Trop Med Hyg\u003c/em\u003e. 2009; 80(3): 452-459.\u003c/li\u003e\n\u003cli\u003eKatrak S, Nayebare P, Rek J, Arinaitwe E, Nankabirwa JI, Kamya M, et al. Clinical consequences of sub microscopic malaria parasitaemia in Uganda. \u003cem\u003eMalar J\u003c/em\u003e. 2018; \u003cstrong\u003e17\u003c/strong\u003e(1): 67.\u003c/li\u003e\n\u003cli\u003eSumbele IUN, Kimbi HK, Ndamukong-Nyanga JL, Nweboh M, Anchang-Kimbi JK, Lum E, et al. Malarial anaemia and anaemia severity in apparently healthy primary school children in urban and rural settings in the Mount Cameroon area: cross sectional survey. \u003cem\u003ePloS One\u003c/em\u003e. 2015; 10(4), e0123549.\u003c/li\u003e\n\u003cli\u003eSumbele IUN, Ning TR, Bopda OS, Nkuo-Akenji T. Variation in malariometric and red cell indices in children in the Mount Cameroon area following enhanced malaria control measures: evidence from a repeated cross-sectional study. \u003cem\u003eMalar J\u003c/em\u003e. 2014; 13(1), 334.\u003c/li\u003e\n\u003cli\u003eBowen HL. Impact of a mass media campaign on bed net use in Cameroon. \u003cem\u003eMalar J\u003c/em\u003e. 2013; 12(1): 36.\u003c/li\u003e\n\u003cli\u003eTeh RN, Sumbele IUN, Nkeudem GA, Meduke DN, Ojong ST, Kimbi HK. Concurrence of CareStart\u0026trade; Malaria HRP2 RDT with microscopy in population screening for \u003cem\u003ePlasmodium falciparum\u003c/em\u003e infection in the Mount Cameroon area: predictors for RDT positivity. \u003cem\u003eTrop Med Health.\u003c/em\u003e 2019; 47:17.\u003c/li\u003e\n\u003cli\u003eNdamukong-Nyanga JL, Kimbi HK, Sumbele IUN, Nana Y, Bertek SC, Ndamukong KJ, et al. A cross-sectional study on the influence of altitude and urbanisation on co-infection of malaria and soil-transmitted helminths in Fako Division, South West Cameroon. \u003cem\u003eInt J Trop Dis and Health\u003c/em\u003e. 2015; 8 (4): 150-164.\u003c/li\u003e\n\u003cli\u003eBryan FJ. The Design and Analysis of Research Studies, UK. University of Otago, Cambridge University Press, 1992.\u003c/li\u003e\n\u003cli\u003eSumbele IUN, Sama SO, Kimbi HK, Taiwe GS. Malaria, moderate to severe anaemia, and malarial anaemia in children at presentation to hospital in the Mount Cameroon area: A cross-sectional study. \u003cem\u003eAnemia\u003c/em\u003e, 2016; Article ID 5725634.\u003c/li\u003e\n\u003cli\u003eCheesbrough, M. District laboratory practice in tropical countries: Part1and2: Cambridge University Press. 2009.\u003c/li\u003e\n\u003cli\u003eKimbi HK, Nkesa SB, Ndamukong-Nyanga JL, Sumbele IUN, Atashili J, Atanga MB. Knowledge and perceptions towards malaria prevention among vulnerable groups in the Buea Health District, Cameroon. \u003cem\u003eBMC Public Health\u003c/em\u003e, 2014; 14(1): 883.\u003c/li\u003e\n\u003cli\u003eBaidjoe A, Stone W, Ploemen I, Shagari S, Grignard L, Osoti V, et al. Combined DNA extraction and antibody elution from filter papers for the assessment of malaria transmission intensity in epidemiological studies. \u003cem\u003eMalar J\u003c/em\u003e. 2013; 12(1): 272.\u003c/li\u003e\n\u003cli\u003eJohnston SP, Pieniazek NJ, Xayavong MV, Slemenda SB, Wilkin PP, da Silva AJ. PCR as a confirmatory technique for laboratory diagnosis of malaria. \u003cem\u003eJ Clin Microbiol\u003c/em\u003e. 2006; 44(3):1087-1089.\u003c/li\u003e\n\u003cli\u003eBhatt S, Weiss D, Cameron E, Bisanzio D, Mappin B, Dalrymple U, et al. The effect of malaria control on \u003cem\u003ePlasmodium falciparum\u003c/em\u003e in Africa between 2000 and 2015. 2015; 526(7572):207.\u003c/li\u003e\n\u003cli\u003eWu L, van den Hoogen LL, Slater H, Walker PG, Ghani AC, Drakeley CJ, et al. Comparison of diagnostics for the detection of asymptomatic \u003cem\u003ePlasmodium falciparum\u003c/em\u003e infections to inform control and elimination strategies. \u003cem\u003eNat\u003c/em\u003e. 2015;528(7580):S86.\u003c/li\u003e\n\u003cli\u003eChen I, Clarke SE, Gosling R, Hamainza B, Killeen G, Magill A, et al. \u0026ldquo;Asymptomatic\u0026rdquo; malaria: a chronic and debilitating infection that should be treated. \u003cem\u003ePLoS Med\u003c/em\u003e. 2016;13(1):e1001942.\u003c/li\u003e\n\u003cli\u003eBaum E, Sattabongkot J, Sirichausinthop J, Kiattibutr K, Jain A, Taghavian O, et al. Common asymptomatic and sub microscopic malaria infections in western Thailand revealed in longitudinal molecular and serological studies: a challenge to malaria elimination. \u003cem\u003eMalar J\u003c/em\u003e. 2016; 15(1): 1-15.\u003c/li\u003e\n\u003cli\u003eDe Mast Q, Brouwers J, Syafruddin D, Bousema T, Baidjoe AY, de Groot PG, et al. Is asymptomatic malaria really asymptomatic? Hematological, vascular and inflammatory effects of asymptomatic malaria parasitemia. \u003cem\u003eJ Infect\u003c/em\u003e. 2015;71(5):587-96.\u003c/li\u003e\n\u003cli\u003eKimbi H, Nana Y, Sumbele I, Anchang-Kimbi J, Lum E, Tonga C et al. Environmental factors and preventive methods against malaria parasite prevalence in rural Bomaka and urban Molyko, Southwest Cameroon. \u003cem\u003eJ Bacteriol Parasitol\u003c/em\u003e. 2013;4(162):4172.\u003c/li\u003e\n\u003cli\u003eKepha S, Nikolay B, Nuwaha F, Mwandawiro CS, Nankabirwa J, Ndibazza J, et al. \u003cem\u003ePlasmodium falciparum\u003c/em\u003e parasitaemia and clinical malaria among school children living in a high transmission setting in western Kenya. \u003cem\u003eMalar J\u003c/em\u003e. 2016; 15(1), 1-13.\u003c/li\u003e\n\u003cli\u003eSarpong N, Owusu-Dabo E, Kreuels B, Fobil JN, Segbaya S, Amoyaw F, et al. Prevalence of malaria parasitaemia in school children from two districts of Ghana earmarked for indoor residual spraying: a cross-sectional study. \u003cem\u003eMalar J\u003c/em\u003e. 2015; 14(1), 1-7.\u003c/li\u003e\n\u003cli\u003eCernetich A, Gaver LS, Jedlicka AE, Klein PW, Kumar N, Scott AL. Involvement of gonadal steroids and gamma interferon in sex differences in response to blood stage malaria infection\u003cem\u003e. Infect Immunol\u003c/em\u003e. 2006; 74 (6): 3190-3203.\u003c/li\u003e\n\u003cli\u003eRodriguez-Barraquer I, Arinaitwe E, Jagannathan P, Kamya MR, Rosenthal PJ, Rek J, et al. Quantification of anti-parasite and anti-disease immunity to malaria as a function of age and exposure. \u003cem\u003eElife\u003c/em\u003e. 2018;7:e35832.\u003c/li\u003e\n\u003cli\u003eBaliraine FN, Afrane YA, Amenya DA, Bonizzoni M, Menge DM, Zhou G, et al. High prevalence of asymptomatic \u003cem\u003ePlasmodium falciparum\u003c/em\u003e infections in a highland area of western Kenya: a cohort study\u003cem\u003e. J Infect Dis.\u003c/em\u003e 2009;200(1):66-74.\u003c/li\u003e\n\u003cli\u003eGanguly S, Saha P, Guha SK, Biswas A, Das S, Kundu PK, et al. High prevalence of asymptomatic malaria in a tribal population in eastern India. \u003cem\u003eJ Clin Microbiol.\u003c/em\u003e 2013;51(5):1439-44.\u003c/li\u003e\n\u003cli\u003eGolassa L, Baliraine FN, Enweji N, Erko B, Swedberg G, Aseffa A. Microscopic and molecular evidence of the presence of asymptomatic \u003cem\u003ePlasmodium falciparum \u003c/em\u003eand \u003cem\u003ePlasmodium vivax\u003c/em\u003e infections in an area with low, seasonal and unstable malaria transmission in Ethiopia. \u003cem\u003eBMC Infect Dis.\u003c/em\u003e 2015;15(1):310.\u003c/li\u003e\n\u003cli\u003eGolassa L, Enweji N, Erko B, Aseffa A, Swedberg G. Detection of a substantial number of sub-microscopic \u003cem\u003ePlasmodium falciparum\u003c/em\u003e infections by polymerase chain reaction: a potential threat to malaria control and diagnosis in Ethiopia. \u003cem\u003eMal J\u003c/em\u003e. 2013;12(1):352.\u003c/li\u003e\n\u003cli\u003eMosha JF, Sturrock HJ, Greenhouse B, Greenwood B, Sutherland CJ, Gadalla N, et al. Epidemiology of subpatent \u003cem\u003ePlasmodium falciparum\u003c/em\u003e infection: implications for detection of hotspots with imperfect diagnostics. \u003cem\u003eMal J\u003c/em\u003e. 2013;12(1):221.\u003c/li\u003e\n\u003cli\u003eIdris ZM, Chan CW, Kongere J, Gitaka J, Logedi J, Omar A, et al. High and heterogeneous prevalence of asymptomatic and sub-microscopic malaria infections on islands in Lake Victoria, Kenya. \u003cem\u003eSci Rep\u003c/em\u003e. 2016, 6:36958.\u003c/li\u003e\n\u003cli\u003eVolkman SK, Neafsey DE, Schaffner SF, Park DJ, Wirth DF. Harnessing genomics and genome biology to understand malaria biology. \u003cem\u003eNat Rev Genet\u003c/em\u003e. 2012;13(5):315.\u003c/li\u003e\n\u003cli\u003eWalk J, Reuling IJ, Behet MC, Meerstein-Kessel L, Graumans W, van Gemert G-J, et al. Modest heterologous protection after \u003cem\u003ePlasmodium falciparum\u003c/em\u003e sporozoite immunization: a double-blind randomized controlled clinical trial. \u003cem\u003eBMC Med\u003c/em\u003e. 2017;15(1):168.\u003c/li\u003e\n\u003cli\u003eElliott SR, Kuns RD, Good MF. Heterologous immunity in the absence of variant-specific antibodies after exposure to sub patent infection with blood-stage malaria. \u003cem\u003eInfect Immun\u003c/em\u003e. 2005; 73(4):2478-2485.\u003c/li\u003e\n\u003cli\u003eLengeler C. Insecticide-treated bed nets and curtains for preventing malaria. \u003cem\u003eCochrane Database of Sys Rev\u003c/em\u003e. 2004; (2):1-46.\u003c/li\u003e\n\u003cli\u003eLin JT, Saunders DL, Meshnick SR. The role of sub microscopic parasitemia in malaria transmission: what is the evidence? \u003cem\u003eTrends in Parasitol\u003c/em\u003e, 2014; 30(4): 183-190.\u003c/li\u003e\n\u003cli\u003eAchidi EA, Apinjoh TO, Anchang-Kimbi JK, Mugri RN, Ngwai AN, Yafi CN. Severe and uncomplicated falciparum malaria in children from three regions and three ethnic groups in Cameroon: prospective study. \u003cem\u003eMalar J\u003c/em\u003e. 2012;11(1):215.\u003c/li\u003e\n\u003cli\u003eApinjoh TO, Anchang-Kimbi JK, Mugri RN, Tangoh DA, Nyingchu RV, Chi HF, et al. The effect of insecticide treated nets (ITNs) on \u003cem\u003ePlasmodium falciparum\u003c/em\u003e infection in rural and semi urban communities in the South West Region of Cameroon. \u003cem\u003ePLoS One\u003c/em\u003e. 2015;10(2):e0116300.\u003c/li\u003e\n\u003cli\u003eKateera F, Mens PF, Hakizimana E, Ingabire CM, Muragijemariya L, Karinda P, et al. Malaria parasite carriage and risk determinants in a rural population: a malariometric survey in Rwanda. \u003cem\u003eMalar J.\u003c/em\u003e 2015; 14(1):16.\u003c/li\u003e\n\u003cli\u003eAsoba GN, Sumbele IUN, Anchang-Kimbi JK, Metuge S, Teh RN. Influence of infant feeding practices on the occurrence of malnutrition, malaria and anaemia in children \u0026le;5 years in the Mount Cameroon area: A cross sectional study. \u003cem\u003ePLoS One. \u003c/em\u003e2019; 14(7): e0219386.\u003c/li\u003e\n\u003cli\u003eUdoh E, Oyo-Ita A, Eyong K, Oringanje C, Oduwole O, Okebe J, et al. Malariometric indices among Nigerian children in rural setting. \u003cem\u003eMalar Res Treat\u003c/em\u003e. 2013;716805.\u003c/li\u003e\n\u003cli\u003ePrice RN, Simpson JA, Nosten F, Luxemburger C, Hkirjaroen L, ter Kuile F, et al. Factors contributing to anemia after uncomplicated falciparum malaria. \u003cem\u003eAm J Trop Med Hyg\u003c/em\u003e. 2001; 65(5):614-22.\u003c/li\u003e\n\u003cli\u003eNgole SIU, Theresa N-A, Moses S, Thomas N, Manka NE, Titanji V. Haematological changes and recovery associated with treated and untreated Plasmodium falciparum infection in children in the Mount Cameroon Region. \u003cem\u003eJournal of Clinical Medicine and Research\u003c/em\u003e. 2010; 2(9): 143-151.\u003c/li\u003e\n\u003cli\u003eNjunda AL, Ngouadjeu DT, Nsagha D, Nyanjoh EM, Kwenti T, Assob NJ. Haematological profile of children with malaria in Kumba Health District, South West Region Cameroon. \u003cem\u003eAfr J Integrated Health\u003c/em\u003e. 2016, 6(2).\u003c/li\u003e\n\u003cli\u003eLadhani S, Lowe B, Cole AO, Kowuondo K, Newton CR. Changes in white blood cells and platelets in children with falciparum malaria: relationship to disease outcome. \u003cem\u003eBr J Haematol\u003c/em\u003e. 2002; 119(3):839-847.\u003c/li\u003e\n\u003cli\u003eSkudowitz R, Katz J, Lurie A, Levin J, Metz J. Mechanisms of thrombocytopenia in malignant tertian malaria. \u003cem\u003eBr Med J\u003c/em\u003e. 1973;2(5865):515-8.\u003c/li\u003e\n\u003cli\u003ePain A, Ferguson DJ, Kai O, Urban BC, Lowe B, Marsh K, et al. Platelet-mediated clumping of \u003cem\u003ePlasmodium falciparum\u003c/em\u003e-infected erythrocytes is a common adhesive phenotype and is associated with severe malaria. \u003cem\u003eProc Nati Acad Sci\u003c/em\u003e. 2001; 98(4):1805-10.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"malaria-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"malj","sideBox":"Learn more about [Malaria Journal](http://malariajournal.biomedcentral.com/)","snPcode":"12936","submissionUrl":"https://submission.nature.com/new-submission/12936/3","title":"Malaria Journal","twitterHandle":"@malariajournal","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Anaemia, asymptomatic malaria, children, haematological parameters, sub-microscopic infection, Plasmodium falciparum, risk factors, Cameroon","lastPublishedDoi":"10.21203/rs.3.rs-310174/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-310174/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003eThe Mount Cameroon area has experienced a 57.2% decline in confirmed malaria cases between 2006 and 2013 with the implementation of different control measures but, the disease is still of public health concern. The objective of the study was to assess the burden of asymptomatic and sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection, altitudinal influence on it, their effect on haematological parameters as well as identify the risk factors of infection.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eMethodology: \u003c/strong\u003eA cross-sectional community-based survey involving 1319 children of both sexes aged 6 months to 14 years was conducted between July 2017 and May 2018. Asymptomatic malaria parasitaemia was confirmed by Giemsa-stained microscopy, sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection by 18S mRNA using nested PCR and full blood count analysis was done using an auto haematology analyser. \u003c/p\u003e\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eMalaria parasite, asymptomatic and sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection and anaemia were prevalent in 36.4%, 34.0%, 43.8% and 62.3% of the children, respectively. The risk of having sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection was highest in children 5‒9 (OR = 3.13, P \u0026lt; 0.001) and 10‒14 years of age (OR = 8.18, P \u0026lt; 0.001), non-insecticide treated net users (OR = 1.69, P \u0026lt; 0.04) and those anaemic (OR = 9.01, P \u0026lt; 0.001). Children with sub-microscopic infection had a significantly lower mean haemoglobin (9.86 ± 1.7 g/dL, P \u0026lt; 0.001), red blood cell counts (4.48 ± 1.1 x 1012/L, P \u0026lt; 0.001), haematocrit (31.92%, P \u0026lt; 0.001), mean corpuscular haemoglobin concentration (313.25 ± 47.36, P = 0.035) and platelet counts (280.83 ± 112.62, P \u0026lt; 0.001) than their negative counterparts. Children \u0026lt;5 years old (73.8%), having asymptomatic (69.8%) and sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection (78.3%) as well as resident in the middle belt (72.7%) had a higher prevalence of anaemia than their peers. \u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConclusion: \u003c/strong\u003eThe significant heterogeneity in the burden of asymptomatic and sub-microscopic \u003cem\u003ePlasmodium\u003c/em\u003e infection in addition to its corollary on haematological variables among children in the different attitudinal sites of the Mount Cameroon Region accentuate the need for strategic context specific planning of malaria control and preventative measures.\u003c/p\u003e","manuscriptTitle":"Asymptomatic and Sub-microscopic Plasmodium Falciparum Infection in Children in the Mount Cameroon Area: a Cross-sectional Study on Altitudinal Influence, Haematological Parameters and Risk Factors","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2021-03-16 22:56:30","doi":"10.21203/rs.3.rs-310174/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major Revision","date":"2021-07-06T00:00:00+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2021-06-10T00:00:00+00:00","index":1,"fulltext":"Recommendation: Reviewer's comments unavailable due to the journal's policy.\n"},{"type":"reviewerAgreed","content":"","date":"2021-05-24T01:00:00+00:00","index":2,"fulltext":""},{"type":"reviewerAgreed","content":"","date":"2021-05-24T00:00:00+00:00","index":1,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2021-03-11T00:00:00+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Malaria Journal","date":"2021-03-10T00:00:00+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2021-03-09T00:00:00+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2021-03-08T23:00:00+00:00","index":"","fulltext":""},{"type":"submitted","content":"Malaria Journal","date":"2021-03-08T09:12:56+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"malaria-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"malj","sideBox":"Learn more about [Malaria Journal](http://malariajournal.biomedcentral.com/)","snPcode":"12936","submissionUrl":"https://submission.nature.com/new-submission/12936/3","title":"Malaria Journal","twitterHandle":"@malariajournal","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"586d1f0d-648b-47f3-85b1-22c1800cbef9","owner":[],"postedDate":"March 16th, 2021","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":3016773,"name":"Infectious Diseases"}],"tags":[],"updatedAt":"2021-09-15T18:59:08+00:00","versionOfRecord":[],"versionCreatedAt":"2021-03-16 22:56:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-310174","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-310174","identity":"rs-310174","version":["v1"]},"buildId":"WrCJVZZCHTDjtuVLN7oU0","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}